EXHIBIT 3.68


                                 SIELKEN, INC.
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                                    BY-LAWS
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                                   ARTICLE 1

                                    OFFICES

     1.1  The principal office of the corporation shall be located in Bryan,
Brazos County, Texas.

     1.2  The corporation may also have offices at such other places both within
and without the State of Texas as the board of directors may from time to time
determine or the business of the corporation may require.

                                  ARTICLE II


                           MEETINGS OF SHAREHOLDERS

     2.1  Meetings of shareholders for any purpose may be held at such time and
place within or without the State of Texas as shall be stated in the notice of
the meeting or in a duly executed waiver of notice thereof.

     2.2  The annual meeting of shareholders shall be held annually at such date
and time as shall be designated from time to time by the board of directors and
stated in the notice of meeting.

     2.3  Special meetings of the shareholders for any purpose or purposes may
be called by the president and shall be called by the president or secretary at
the request in writing of a majority of the board of directors, or at the
request in writing of shareholders owning one-tenth of all the shares entitled
to vote at the meetings.  A request for a special meeting shall state the
purpose or purposes of the proposed meeting, and business transacted at any
special meeting of shareholders shall be limited to the purposes stated in the
notice.


     2.4  Written notice stating the place, day and hour of the meeting and, in
the case of a special meeting, the purpose or purposes for which the meeting is
called, shall be delivered not less than ten nor more than fifty days before the
date of the meeting, either personally or by mail, by or at the direction of the
president, the secretary, or the officer or persons calling the meeting, to each
shareholder of record entitled to vote at such meeting.

     2.5  The holders of a majority of the shares issued and outstanding and
entitled to vote thereat, present in person or represented by proxy, shall
constitute a quorum at all meetings of the shareholders for the transaction of
business except as otherwise provided by statute or by the articles of
incorporation.  If, however, a quorum shall not be present or represented at any
meeting of the shareholders, the shareholders entitled to vote thereat, present
in person or represented by proxy, shall have power to adjourn the meeting from
time to time, without notice other than announcement at the meeting, until a
quorum shall be present or represented.  At such adjourned meeting, provided a
quorum shall be present or represented thereat, any business may be transacted
which might have been transacted if the meeting had been held in accordance with
the original notice thereof.

     2.6  If a quorum is present at any meeting, the vote of the holders of a
majority of the shares entitled to vote, present in person or represented by
proxy, shall decide any questions brought before such meeting, unless the
question is one upon which a different vote is required by law or by the
articles of incorporation.

     2.7  Each outstanding share having voting power shall be entitled to one
vote on each matter submitted to a vote at a meeting of shareholders.  A
shareholder may vote either in person or by proxy executed in writing by the
shareholder or by his duly authorized attorney-in-fact.

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     2.8  Any action required or which may be taken at a meeting of the
shareholders may be taken without a meeting if a consent in writing, setting
forth the action so taken, shall be signed by all the shareholders entitled to
vote with respect to the subject matter thereof.

                                  ARTICLE III

                                   DIRECTORS

     3.1  The number of directors which shall constitute the whole board of
directors shall be not less than one. Such number of directors shall from time
to time be fixed and determined by the directors and shall be set forth in the
notice of any meeting of stockholders held for the purpose of electing
directors. The directors shall be elected at the annual meeting of stockholders,
except as provided in Section 3.2, and each director elected shall hold office
until his successor shall be elected and qualify. Directors need not be
residents of Texas or stockholders of the corporation.

     3.2  Any vacancy occurring in the board of directors may be filled by a
majority of the remaining directors though less than a quorum of the board of
directors. A director elected to fill a vacancy shall be elected for the
unexpired term of his predecessor in office.

     3.3  The number of directors may be increased or decreased from time to
time as provided in these by-laws but no decrease shall have the effect of
shortening the term of any incumbent director. Any directorship to be filled by
reason of an increase in the number of directors shall be filled by election at
an annual or special meeting of shareholders.

     3.4  Any director may be removed either for or without cause at any special
meeting of shareholders duly called and held for such purpose.

                      MEETINGS OF THE BOARD OF DIRECTORS

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     3.5  Meetings of the board of directors, regular or special, may be held
either within or without the State of Texas.

     3.6  The first meeting of each newly elected board of directors shall be
held at such time and place as shall be fixed by the vote of the shareholders at
the annual meeting and no notice of such meeting shall be necessary to the newly
elected directors in order legally to constitute the meeting, provided a quorum
shall be present.  In the event that the shareholders fail to fix the time and
place of such first meeting, it shall be held without notice immediately
following the annual meeting of shareholders, and at the same place, unless by
the unanimous consent of the directors then elected and serving such time or
place shall be changed.

     3.7  Regular meetings of the board of directors may be held upon such
notice, or without notice, and at such time and at such place as shall from time
to time be determined by the board.

     3.8  Special meetings of the board of directors may be called by the
chairman of the board of directors or the president and shall be called by the
secretary on the written request of two directors.  Notice of each special
meeting of the board of directors shall be given to each director at least ten
days before the date of the meeting.

     3.9.  Attendance of a director at any meeting shall constitute a waiver of
notice of such meeting, except where a director attends for the express purpose
of objecting to the transaction of any business on the ground that the meeting
is not lawfully called or convened. Except as may be otherwise provided by law
or by the articles of incorporation or by the by-laws, neither the business to
be transacted at, nor the purpose of, any regular or special meeting of the
board of directors need be specified in the notice or waiver of notice of such
meeting.

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     3.10  At all meetings of the board of directors a majority of the directors
shall constitute a quorum for the transaction of business and the act of a
majority of the directors present at any meeting at which there is a quorum
shall be the act of the board of directors, unless otherwise specifically
provided by law, the articles of incorporation or the by-laws.  If a quorum
shall not be present at any meeting of directors, the directors present thereat
may adjourn the meeting from time to time, without notice other than
announcement at the meeting, until a quorum shall be present.

     3.11  The board of directors, by resolution passed by a majority of the
full board, may from time to time designate a member or members of the board to
constitute committees, including an executive committee, which shall in each
case consist of one or more directors and shall have and may exercise such
powers, as the board may determine and specify in the respective resolutions
appointing them. A majority of all the members of any such committee may
determine its action and fix the time and place of its meetings, unless the
board of directors shall otherwise provide. The board of directors shall have
power at any time to change the number, subject as aforesaid, and members of any
such committee, to fill vacancies and to discharge any such committee.

     3.12  Any action required or permitted to be taken at a meeting of the
board of directors or any committee may be taken without a meeting if a consent
in writing, setting forth the action so taken, is signed by all the members of
the board of directors or committee, as the case may be.

     3.13  By resolution of the board of directors, the directors may be paid
their expenses, if any, of attendance at each meeting of the board of directors
and may be paid a fixed sum for attendance at each meeting of the board of
directors or a stated salary as director. No such

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payment shall preclude any director from serving the corporation in any other
capacity and receiving compensation therefor.

                                  ARTICLE IV

                                    NOTICES

     4.1  Any notice to directors or shareholders shall be in writing and shall
be delivered personally or mailed to the directors or shareholders at their
respective addresses appearing on the books of the corporation. Notice by mail
shall be deemed to be given at the time when the same shall be deposited in the
United States mail, postage prepaid. Notice to directors may also be given by
telegram.

     4.2  Whenever any notice is required to be given under the provisions of
the statutes or of the articles of incorporation or of these by-laws, a waiver
thereof in writing signed by the person or persons entitled to such notice,
whether before or after the time stated therein, shall be deemed equivalent to
the giving of such notice.

                                   ARTICLE V

                                   OFFICERS

     5.1  The officers of the corporation shall be elected by the board of
directors and shall consist of a president, a vice president, a secretary and a
treasurer or a secretary/treasurer.  The board of directors may also elect a
chairman of the board, an assistant president, additional vice presidents, and
one or more assistant secretaries and assistant treasurers.  Two or more offices
may be held by the same person, except that the offices of president and
secretary may not be held by the same person.

     5.2  The board of directors shall elect a president, one or more vice
presidents, a secretary and a treasurer or secretary/treasurer, none of whom
need be a member of the board.

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The board of directors shall have the power to enter into contracts for the
employment and compensation of officers for such terms as the board deems
advisable.

     5.3  The board of directors may appoint such other officers and assistant
officers and agents as it shall deem necessary, who shall hold their offices for
such terms and shall have such authority and exercise such powers and perform
such duties as shall be determined from time to time by the board by resolution
not inconsistent with these by-laws.

     5.4  The salaries of all officers and agents of the corporation shall be
fixed by the board of directors.

     5.5  The officers of the corporation shall hold office until their
successors are elected or appointed and qualify, or until their death or until
their resignation or removal from office. Any officer elected or appointed by
the board of directors may be removed at any time by the board, but such removal
shall be without prejudice to the contract rights, if any, of the person so
removed. Election or appointment of any officer or agent shall not of itself
create contract rights. Any vacancy occurring in any office of the corporation
by death, resignation, removal or otherwise shall be filled by the board of
directors.

                           THE CHAIRMAN OF THE BOARD

     5.6  The chairman of the board, if one be elected, shall preside at all
meetings of the board of directors and shall have such other powers and duties
as may from time to time be prescribed by the board of directors, upon written
directions given to him pursuant to resolutions duly adopted by the board of
directors.

                                 THE PRESIDENT

     5.7  The president shall be the chief executive officer of the corporation,
shall have general and active management of the business of the corporation and
shall see that all orders and

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resolutions of the board of directors are carried into effect. He shall preside
at all meetings of the shareholders.

                              THE VICE PRESIDENT

     5.8   The vice presidents in the order of their seniority, unless otherwise
determined by the board of directors, shall, in the absence or disability of the
president, perform the duties and have the authority and exercise the powers of
the president.  They shall perform such other duties and have such other
authority and powers as the board of directors may from time to time prescribe
or as the president may from time to time delegate.

                    THE SECRETARY AND ASSISTANT SECRETARIES

     5.9   The secretary shall attend all meetings of the board of directors and
all meetings of shareholders and record all of the proceedings of the meetings
of the board of directors and of the shareholders in a minute book to be kept
for that purpose and shall perform like duties for the standing committees when
required.  He shall give, or cause to be given, notice of all meetings of the
shareholders and special meetings of the board of directors, and shall perform
such other duties as may be prescribed by the board of directors or president,
under whose supervision he shall be.  He shall keep in safe custody the seal of
the corporation and, when authorized by the board of directors, shall affix the
same to any instrument requiring it and, when so affixed, it shall be attested
by his signature or by the signature of an assistant secretary or of the
treasurer.

     5.10  The assistant secretaries in the order of their seniority, unless
otherwise determined by the board of directors, shall, in the absence or
disability of the secretary, perform the duties and exercise the powers of the
secretary.  They shall perform such other duties and have such other powers as
the board of directors may from time to time prescribe or as the president may
from time to time delegate.

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                    THE TREASURER AND ASSISTANT TREASURERS

     5.11  The treasurer shall have custody of the corporate funds and
securities and shall keep full and accurate accounts and records of receipts,
disbursements and other transactions in books belonging to the corporation, and
shall deposit all moneys and other valuable effects in the name and to the
credit of the corporation in such depositories as may be designated by the board
of directors.

     5.12  The treasurer shall disburse the funds of the corporation as may be
ordered by the board of directors, taking proper vouchers for such
disbursements, and shall render the president and the board of directors, at its
regular meetings, or when the president or board of directors so requires, an
account of all his transactions as treasurer and of the financial condition of
the corporation.

     5.13  If required by the board of directors, the treasurer shall give the
corporation a bond of such type, character and amount as the board of directors
may require.

     5.14  The assistant treasurers in the order of their seniority, unless
otherwise determined by the board of directors, shall, in the absence or
disability of the treasurer, perform the duties and exercise the powers of the
treasurer.  They shall perform such other duties and have such other powers as
the board of directors may from time to time prescribe or the president may from
time to time delegate.

                                  ARTICLE VI

                       CERTIFICATES REPRESENTING SHARES

     6.1  The shares of the corporation shall be represented by certificates
signed by the president or a vice president and the secretary or an assistant
secretary of the corporation, and may be sealed with the seal of the corporation
or a facsimile thereof.

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     6.2  The signatures of the president or vice president and the secretary or
assistant secretary upon a certificate may be facsimiles if the certificate is
counter-signed by a transfer agent, or registered by a registrar, other than the
corporation itself or an employee of the corporation.  In case any officer who
has signed or whose facsimile signature has been placed upon such certificate
shall have ceased to be such officer before such certificate is issued, it may
be issued by the corporation with the same effect as if he were such officer at
the date of its issue.

                               LOST CERTIFICATES

     6.3  The board of directors may direct a new certificate to be issued in
place of any certificate theretofore issued by the corporation alleged to have
been lost or destroyed.  When authorizing such issue of a new certificate, the
board of directors, in its discretion and as a condition precedent to the
issuance thereof, may prescribe such terms and conditions as it deems expedient
and may require such indemnities as it deems adequate to protect the corporation
from any claim that may be made against it with respect to any such certificate
alleged to have been lost or destroyed.

     6.4  Upon surrender to the corporation or the transfer agent of the
corporation of a certificate representing shares duly endorsed or accompanied by
proper evidence of succession, assignment or authority to transfer, a new
certificate shall be issued to the person entitled thereto and the old
certificate cancelled and the transaction recorded upon the books of the
corporation.

                           CLOSING OF TRANSFER BOOKS

     6.5  For the purpose of determining shareholders entitled to notice of or
to vote at any meeting of shareholders, or any adjournment thereof, or entitled
to receive payment of any dividend, or in order to make a determination of
shareholders for any other proper purpose, the board of directors may provide
that the stock transfer books shall be closed for a stated period

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but not to exceed, in any case, fifty days. If the stock transfer books shall be
closed for the purpose of determining shareholders entitled to notice of or to
vote at a meeting of shareholders, such books shall be closed for at least ten
days immediately preceding such meeting. In lieu of closing the stock transfer
books, the board of directors may fix in advance a date as the record date for
any such determination of shareholders, such date in any case to be not more
than fifty days and, in case of a meeting of shareholders, not less than ten
days prior to the date on which the particular action, requiring such
determination of shareholders, is to be taken. If the stock transfer books are
not closed and no record date is fixed for the determination of shareholders
entitled to notice of or to vote at a meeting of shareholders, or shareholders
entitled to receive payment of a dividend, the date on which notice of the
meeting is mailed or the date on which the resolution of the board of directors
declaring such dividend is adopted, as the case may be, shall be the record date
for such determination of shareholders. When a determination of shareholders
entitled to vote at any meeting of shareholders has been made as provided in
this section, such determination shall be applied to any adjournment thereof
except where the determination has been made through the closing of the stock
transfer books and the stated period of closing has expired.

                            REGISTERED SHAREHOLDERS

     6.6  The corporation shall be entitled to recognize the exclusive right of
a person registered on its books as the owner of shares to receive dividends,
and to vote as such owner, and shall not be bound to recognize any equitable or
other claim to or interest in such share or shares on the part of any other
person, whether or not it shall have express or other notice thereof, except as
otherwise provided by the laws of Texas.

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                             LIST OF SHAREHOLDERS

     6.7  The officer or agent having charge of the transfer books for shares
shall make, at least ten days before each meeting of shareholders, a complete
list of the shareholders entitled to vote at such meeting, arranged in
alphabetical order, with the address of each and the number of shares held by
each, which list, for a period of ten days prior to such meeting, shall be kept
on file at the registered office of the corporation and shall be subject to
inspection by any shareholder at any time during usual business hours.  Such
list shall also be produced and kept open at the time and place of the meeting
and shall be subject to the inspection of any shareholder during the whole time
of the meeting.  The original share ledger or transfer book, or a duplicate
thereof, shall be prima facie evidence as to who are the shareholders entitled
to examine such list or share ledger or transfer book or to vote at any meeting
of the shareholders.

                                  ARTICLE VII

                              GENERAL PROVISIONS

                                   DIVIDENDS

     7.1  Subject to the provisions of the articles of incorporation relating
thereto, if any, dividends may be declared by the board of directors, in its
discretion, at any regular or special meeting, pursuant to law.  Dividends may
be paid in cash, in property or in the corporation's own shares, subject to any
provisions of the articles of incorporation.

     7.2  Before payment of any dividend, there may be set aside out of any
funds of the corporation available for dividends such sum or sums as the
directors from time to time, in their absolute discretion, think proper as a
reserve fund for meeting contingencies, or for equalizing dividends, or for
repairing or maintaining any property of the corporation, or for such other

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purpose as the directors shall think conducive to the interest of the
corporation, and the directors may modify or abolish any such reserve in the
manner in which it was created.

                                    CHECKS

     7.3  All checks or demands for money and notes of the corporation shall be
signed by such officer or officers or such other person or persons as the board
of directors may from time to time designate.

                                  FISCAL YEAR

     7.4  The fiscal year of the corporation shall be fixed by resolution of the
board of directors.

                                     SEAL

     7.5  The corporate seal shall be in such form as may be prescribed by the
board of directors.  The seal may be used by causing it or a facsimile thereof
to be impressed or affixed or in any manner reproduced.

                               BOOKS AND RECORDS

     7.6  The corporation shall keep correct and complete books and records of
account and shall keep minutes of the proceedings of its shareholders and board
of directors, and shall keep at its registered office or principal place of
business, or at the office of its transfer agent or registrar, a record of its
shareholders, giving the names and addresses of all shareholders and the number
and class of the shares held by each.

                                 ARTICLE VIII

                                  AMENDMENTS

     8.1  The by-laws may be altered, amended, or repealed or new by-laws may be
adopted by a majority of the whole board of directors at any regular or special
meeting.

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                                  ARTICLE IX

                   INDEMNIFICATION OF DIRECTORS AND OFFICERS

     9.1  The corporation shall indemnify any director or officer or former
director or officer of the corporation, or any person who may have served at its
request as a director or officer or former director or officer of another
corporation in which it owns shares of capital stock or of which it is a
creditor, against expenses actually and necessarily incurred by him in
connection with the defense of any action, suit, or proceeding, whether civil or
criminal, in which he is made a party by reason of being or having been such
director or officer, except in relation to matters as to which he shall be
adjudged in such action, suit or proceeding to be liable for negligence or
misconduct in performance of duty. The corporation shall also reimburse any such
director or officer or former director or officer or any such person serving or
formerly serving in the capacities set forth in the first sentence above at the
request of the corporation for the reasonable cost of settlement of any such
action, suit or proceeding, if it shall be found by a majority of the directors
not involved in the matter in controversy, whether or not a quorum, that it was
in the best interest of the corporation that such settlement be made, and that
such director or officer or former director or officer or such person was not
guilty of negligence or misconduct in performance of duty. Such indemnification
shall not be deemed exclusive of any other rights to which such director or
officer or former director or officer or such person may be entitled, under any
by-law, agreement, insurance policy or vote of shareholders, or otherwise.

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