SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                  SCHEDULE TO
                               (AMENDMENT NO. 3)

        TENDER OFFER STATEMENT UNDER SECTION 14(D)(1) OR 13(E)(1) OF THE
                         SECURITIES EXCHANGE ACT OF 1934
                               (FINAL AMENDMENT)
                                      AND
                                 SCHEDULE 13D/A
                   UNDER THE SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. 18)

                   Davidson Diversified Real Estate II, L.P.
- --------------------------------------------------------------------------------
                        (Name of Subject Company (Issuer)

                        AIMCO Properties, L.P. -- Offeror
                  Apartment Investment and Management Company
                                 AIMCO-GP, Inc.
                     Davidson Diversified Properties, Inc.
- --------------------------------------------------------------------------------
                     (Names of Filing Persons  -- Offerors)

                            Limited Partnership Units
- --------------------------------------------------------------------------------
                           (Title of Class Securities)

                                      None
- --------------------------------------------------------------------------------
                       (CUSIP Number of Class Securities)

                                 Martha L. Long
                   Apartment Investment and Management Company
                     4582 Ulster Street Parkway, Suite 1100
                             Denver, Colorado 80237
                                 (303) 757-8101
- --------------------------------------------------------------------------------
           (Name, address, and telephone numbers of person authorized
       to receive notices and communications on behalf of filing persons)

                                    Copy to:

                                 Joseph A. Coco
                    Skadden, Arps, Slate, Meagher & Flom LLP
                                Four Times Square
                            New York, New York 10036
                                 (212) 735-3000

                                       and

                              Jonathan L. Friedman
                    Skadden, Arps, Slate, Meagher & Flom LLP
                             300 South Grand Avenue
                          Los Angeles, California 90071
                                 (213) 687-5000

                            Calculation of Filing Fee

<Table>
<Caption>
Transaction valuation*                                   Amount of filing fee
- ----------------------                                   --------------------
                                                      
$2,480,132.72                                            $314.23
</Table>


                                       1




*        For purposes of calculating the fee only. This amount assumes the
         purchase of 604 units of limited partnership interest of the
         subject partnership for $4,106.18 per unit. The amount of the filing
         fee, calculated in accordance with Section 14(g)(1)(B)(3) and Rule 0-11
         (d) under the Securities Exchange Act of 1934, as amended, equals
         $126.70 per million of the aggregate amount of cash offered by the
         bidder.
[X]      Check the box if any part of the fee is offset as provided by Rule
         0-11(a)(2) and identify the filing with which the offsetting fee was
         previously paid. Identify the previous filing by registration statement
         number, or the Form or Schedule and the date of its filing.

Amount Previously Paid: $314.23             Filing Party: AIMCO Properties, L.P.

Form or Registration No.: Schedule TO       Date Filed: June 14, 2004

[ ] Check the box if the filing relates solely to preliminary communications
made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the
statement relates:

[X] third-party tender offer subject to Rule 14d-1

[ ] issuer tender offer subject to Rule 13e-4

[X] going-private transaction subject to Rule 13e-3

[X] amendment to Schedule 13D under Rule 13d-2

Check the following box if the filing is a final amendment reporting the results
of the tender offer: [X]



                                       2


CUSIP NO. NONE

- --------------------------------------------------------------------------------
1   NAME OF REPORTING PERSONS. AIMCO PROPERTIES, L.P.
    I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) 84-1275721


- --------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
    (a) [ ]

    (b) [X]
- --------------------------------------------------------------------------------
3   SEC USE ONLY


- --------------------------------------------------------------------------------
4   SOURCE OF FUNDS (SEE INSTRUCTIONS)
    WC

- --------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
    OR 2(e) [ ]

- --------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION
    Delaware

- --------------------------------------------------------------------------------
                7   SOLE VOTING POWER
  NUMBER OF         --
   SHARES
BENEFICIALLY   -----------------------------------------------------------------
  OWNED BY      8   SHARED VOTING POWER
   EACH             647.25 Units
 REPORTING
  PERSON       -----------------------------------------------------------------
   WITH         9   SOLE DISPOSITIVE POWER
                    --

               -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER
                    647.25 Units

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     647.25 Units

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
     (SEE INSTRUCTIONS)  [ ]

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
     Approximately 52.87%

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
     PN

- --------------------------------------------------------------------------------

                                       3


CUSIP NO. NONE

- --------------------------------------------------------------------------------
1   NAME OF REPORTING PERSONS. AIMCO-GP, INC.
    I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)


- --------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
    (a) [ ]

    (b) [X]
- --------------------------------------------------------------------------------
3   SEC USE ONLY


- --------------------------------------------------------------------------------
4   SOURCE OF FUNDS (SEE INSTRUCTIONS)
    Not Applicable

- --------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
    OR 2(e) [ ]

- --------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION
    Delaware

- --------------------------------------------------------------------------------
                7   SOLE VOTING POWER
  NUMBER OF         --
   SHARES
BENEFICIALLY   -----------------------------------------------------------------
  OWNED BY      8   SHARED VOTING POWER
   EACH             647.25 Units
 REPORTING
  PERSON       -----------------------------------------------------------------
   WITH         9   SOLE DISPOSITIVE POWER
                    --

               -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER
                    647.25 Units

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     647.25 Units

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
     (SEE INSTRUCTIONS)  [ ]

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
     Approximately 52.87%

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
     CO

- --------------------------------------------------------------------------------


                                       4


CUSIP NO. NONE

- --------------------------------------------------------------------------------
1   NAME OF REPORTING PERSONS. APARTMENT INVESTMENT AND MANAGEMENT COMPANY
    I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) 84-1259577


- --------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
    (a) [ ]

    (b) [X]
- --------------------------------------------------------------------------------
3   SEC USE ONLY


- --------------------------------------------------------------------------------
4   SOURCE OF FUNDS (SEE INSTRUCTIONS)
    Not Applicable

- --------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
    OR 2(e) [ ]

- --------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION
    Maryland

- --------------------------------------------------------------------------------
                7   SOLE VOTING POWER
  NUMBER OF         --
   SHARES
BENEFICIALLY   -----------------------------------------------------------------
  OWNED BY      8   SHARED VOTING POWER
   EACH             647.25 Units
 REPORTING
  PERSON       -----------------------------------------------------------------
   WITH         9   SOLE DISPOSITIVE POWER
                    --

               -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER
                    647.25 Units

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     647.25 Units

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
     (SEE INSTRUCTIONS)  [ ]

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
     Approximately 52.87%

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
     CO

- --------------------------------------------------------------------------------

                                       5


CUSIP NO. NONE

- --------------------------------------------------------------------------------
1   NAME OF REPORTING PERSONS. INSIGNIA PROPERTIES, L.P.
    I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)


- --------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
    (a) [ ]

    (b) [X]
- --------------------------------------------------------------------------------
3   SEC USE ONLY


- --------------------------------------------------------------------------------
4   SOURCE OF FUNDS (SEE INSTRUCTIONS)
    Not Applicable

- --------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
    OR 2(e) [ ]

- --------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION
    Delaware

- --------------------------------------------------------------------------------
                7   SOLE VOTING POWER
  NUMBER OF         --
   SHARES
BENEFICIALLY   -----------------------------------------------------------------
  OWNED BY      8   SHARED VOTING POWER
   EACH             158.50 Units
 REPORTING
  PERSON       -----------------------------------------------------------------
   WITH         9   SOLE DISPOSITIVE POWER
                    --

               -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER
                    158.50 Units

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     158.50 Units

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
     (SEE INSTRUCTIONS)  [ ]

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
     Approximately 12.95%

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
     PN

- --------------------------------------------------------------------------------


                                       6




CUSIP NO. NONE

- --------------------------------------------------------------------------------
1   NAME OF REPORTING PERSONS. COOPER RIVER PROPERTIES, L.L.C.
    I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)


- --------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
    (a) [ ]

    (b) [X]
- --------------------------------------------------------------------------------
3   SEC USE ONLY


- --------------------------------------------------------------------------------
4   SOURCE OF FUNDS (SEE INSTRUCTIONS)
    Not Applicable

- --------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
    OR 2(e) [ ]

- --------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION
    Delaware

- --------------------------------------------------------------------------------
                7   SOLE VOTING POWER
  NUMBER OF         --
   SHARES
BENEFICIALLY   -----------------------------------------------------------------
  OWNED BY      8   SHARED VOTING POWER
   EACH             122.75 Units
 REPORTING
  PERSON       -----------------------------------------------------------------
   WITH         9   SOLE DISPOSITIVE POWER
                    --

               -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER
                    122.75 Units

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     122.75 Units

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
     (SEE INSTRUCTIONS)  [ ]

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
     Approximately 10.03%

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
     OO

- --------------------------------------------------------------------------------


                                       7




CUSIP NO. NONE

- --------------------------------------------------------------------------------
1   NAME OF REPORTING PERSONS. AIMCO/IPT, INC.
    I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)


- --------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
    (a) [ ]

    (b) [X]
- --------------------------------------------------------------------------------
3   SEC USE ONLY


- --------------------------------------------------------------------------------
4   SOURCE OF FUNDS (SEE INSTRUCTIONS)
    Not Applicable

- --------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
    OR 2(e) [ ]

- --------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION
    Delaware

- --------------------------------------------------------------------------------
                7   SOLE VOTING POWER
  NUMBER OF         --
   SHARES
BENEFICIALLY   -----------------------------------------------------------------
  OWNED BY      8   SHARED VOTING POWER
   EACH             158.50 Units
 REPORTING
  PERSON       -----------------------------------------------------------------
   WITH         9   SOLE DISPOSITIVE POWER
                    --

               -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER
                    158.50 Units

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     158.50 Units

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
     (SEE INSTRUCTIONS)  [ ]

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
     Approximately 12.95%

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
     CO

- --------------------------------------------------------------------------------


                                       8

        AMENDMENT NO. 3 TO SCHEDULE TO/AMENDMENT NO. 18 TO SCHEDULE 13D

         This Statement constitutes (a) Amendment No. 3 to the Tender Offer
Statement and Rule 13e-3 Transaction Statement on Schedule TO, as amended by
Amendment No. 1 and Amendment No. 2 thereto (the "Schedule TO"), filed by AIMCO
Properties, L.P., AIMCO-GP, Inc., Apartment Investment and Management Company
and Davidson Diversified Properties, Inc. relating to the offer by AIMCO
Properties, L.P. to purchase units of limited partnership interest ("Units") of
Davidson Diversified Real Estate II, L.P., a Delaware limited partnership (the
"Partnership"), at a price of $4,106.18 per unit in cash, subject to the
conditions set forth in the Litigation Settlement Offer dated June 14, 2004, and
in the related Letter of Transmittal (which, together with any supplements or
amendments, collectively constitute the "Offer"); and (b) Amendment No. 18 to
the Schedule 13D filed by AIMCO Properties, L.P., AIMCO-GP, Inc., Apartment
Investment and Management Company, AIMCO IPLP, L.P., Cooper River Properties,
L.L.C. and Insignia Properties, L.P. (the "Schedule 13D"). Copies of the
Litigation Settlement Offer and the Letter of Transmittal are filed as Exhibits
(a)(1) and (a)(2), respectively, to the Schedule TO.  The item numbers and
responses thereto below are in accordance with the requirements of Schedule TO.
Unless defined herein, capitalized terms used and not otherwise defined herein
have the respective meanings ascribed to such terms in the Litigation Settlement
Offer.

         At midnight, New York City time, on August 13, 2004, the Offer expired
pursuant to its terms.  A total of 27 units, representing approximately 1.2% of
the outstanding units, were validly tendered and not withdrawn pursuant to the
Offer.  AIMCO Properties, L.P. has accepted for payment all of those units.


                                       9





                                    SIGNATURE

                  After due inquiry and to the best of its knowledge and belief,
the undersigned hereby certify that the information set forth in this statement
is true, complete and correct.

Date:  August 18, 2004
                                           AIMCO PROPERTIES, L.P.

                                           By:  AIMCO-GP, INC.
                                                Its General Partner


                                           By:  /s/ Martha L. Long
                                                -------------------------------
                                                Martha L. Long
                                                Senior Vice President


                                           APARTMENT INVESTMENT AND
                                           MANAGEMENT COMPANY


                                           By:  /s/ Martha L. Long
                                                -------------------------------
                                                Martha L. Long
                                                Senior Vice President


                                           AIMCO-GP, INC.



                                           By:  /s/ Martha L. Long
                                                -------------------------------
                                                Martha L. Long
                                                Senior Vice President



                                           DAVIDSON DIVERSIFIED PROPERTIES, INC.



                                           By:  /s/ Martha L. Long
                                                -------------------------------
                                                Martha L. Long
                                                Senior Vice President


                                           COOPER RIVER PROPERTIES, L.L.C.



                                           By:  AIMCO PROPERTIES, L.P.
                                                Its Managing Member


                                           By:  AIMCO-GP, INC.
                                                Its General Partner


                                           By:  /s/ Martha L. Long
                                                -------------------------------
                                                Martha L. Long
                                                Senior Vice President

                                           INSIGNIA PROPERTIES, L.P.


                                           By:  AIMCO/IPT, INC.
                                                Its General Partner


                                           By:  /s/ Martha L. Long
                                                -------------------------------
                                                Martha L. Long
                                                Senior Vice President


                                           AIMCO/IPT, INC.


                                           By:  /s/ Martha L. Long
                                                -------------------------------
                                                Martha L. Long
                                                Senior Vice President


                                       10