THIRD AMENDMENT
                       TO LEASE AGREEMENT                      EXHIBIT 10.66   
                                
     THIS THIRD AMENDMENT made and entered into as of the 20th day of August,
1997 by and between Toboll Properties Limited Partnership, whose address for
purposes of this Agreement is 2001 Crestwood Road, Sioux Falls, South Dakota  
57105 ("Lessor") and Sioux Falls Structures, Inc. (formerly Modular Structures 
of South Dakota, Inc.), whose address is Rural Route 4, Box 40, Sioux Falls, 
South Dakota 57107 ("Lessee");

     WITNESSETH:

     1.   Background.

          1.1  Toboll Corporation (formerly Sioux Falls Structures, Inc.) and 
Lessee have entered into a Lease dated April 15, 1985 (the "Lease") covering the
following described real property and improvements thereon, located in Minnehaha
County, South Dakota, to-wit (the "Leased Premises"):
     
     Lots 8 and 10, except the North 916.5 feet of the East 27 feet of Lot 10, 
     of Northwestern Industrial Park in the West Half of the North Half of the 
     Northwest Quarter (W1/2N1/2NW1/4) of Section 18, Township 102 North, Range 
     49 West, according to the recorded plat thereof.
     
          1.2  Toboll Properties, a South Dakota general partnership, was the 
successor to Toboll Corporation and Lessor is the successor of Toboll 
Properties.
     
          1.3  The Lease has been amended by an agreement dated February 3, 1988
(the "First Amendment"), and by a second agreement dated December 31, 1989 (the
"Second Amendment").

          1.4  Under the Second Amendment, the term of the Lease was extended to
April 15, 1994 and Lessee was granted the option to further extend the Lease for
three successive periods of two years each on terms and conditions described in 
the Second Amendment.  Lessee has thus far exercised two of those options.

          1.5  Lessor and Lessee now deem it in their mutual best interests to 
amend the Lease a third time by this Agreement (the "Third Amendment").
     
     2.   Grant of Additional Option.   Lessor hereby grants to Lessee the 
option to extend the term of the Lease for a three-year term in addition to all 
other options previously granted by the First Amendment or Second Amendment, 
commencing on the day following expiration of the last extension period granted 
under the Second Amendment.

     3.   Method of Exercise. The extension option granted by this Third 
Amendment must be exercised by written notice from the Lessee to Lessor at least
90 days prior to the expiration of the then extended term explicitly stating 
that Lessee exercises its right to extend the term of this Lease under the Third
Amendment.

     4.   Effect of Exercise.

          4.1  Lessee's attempted exercise of the extension option granted by 
this Third Amendment shall not be effective to extend the term of this Lease 
unless:

               (a)  Lessee is not in default of the Lease or the terms of the 
First Amendment, Second Amendment or this Third Amendment at the time of the 
exercise; and

               (b)  No further event of default occurs after the notice of 
exercise; and

               (c)  Lessee's notice of exercise complies with the requirements
of P 3; and

               (d)  Lessee shall have exercised all extension options granted 
under the Second Amendment.

          4.2  Except as described in P4.1, on Lessee's notice of exercise, this
Lease, subject to the terms of this Third Amendment, shall be deemed to be 
extended and the term thereof extended for a period of three years from the date
of the expiration of the last extended term during which such notice is given, 
without execution of any further lease, document or instrument.

     5.   Terms Applicable to Extension Period.

          5.1  The annual rent applicable to each year of the Lease term 
extension provided in this Agreement shall be $68,000.00 per year, payable in 
equal consecutive monthly installments of $5,666.67 payable as and at the times 
described in the Lease.

          5.2  Lessee shall have no option to extend the Lease beyond the 
expiration of the extension term covered by this Third Amendment.

          5.3  The terms and conditions described in the Lease shall be fully 
applicable during the extended term covered by this Third Amendment.

     6.   Rent Adjustment Applicable to Second Amendment.   Unless Lessee 
improves the Leased Premises by constructing a warehouse and accomplishing 
office remodeling at a total minimum cost of $30,000.00 according to plans and 
specifications approved by Lessor, the base rental applicable to the last 
extension term granted under the Second Amendment shall increase to $68,048.00 
per year.  Lessee's exercise of the remaining extension option granted by the 
Second Amendment shall constitute Lessee's agreement to be subject to the 
conditional rent adjustment as described in this paragraph.

     7.   Binding Effect.     Except as modified hereby, the Lease and the 
Second Amendment shall remain in full force and effect according to their 
original terms.  The parties acknowledge that the First Amendment was superseded
in its entirety by the Second Amendment.

                                        TOBOLL PROPERTIES LIMITED
                                        PARTNERSHIP                             

Dated: 8/27, 1997                       By  \J F Toboll                         
                                        Its: General Partner                   


                                        SIOUX FALLS STRUCTURES, INC.

Dated: 8/20, 1997                       By  \Edward C. Craig                   
                                        Its: Pres