UNITED STATES
               SECURITIES AND EXCHANGE COMMISSION

                    Washington, D.C.  20549


                          SCHEDULE 13D


           Under the Securities Exchange Act of 1934
                         AMENDMENT NO.1

    Southwest Royalties Institutional Income Fund X-C, L.P.
                        (Name of Issuer)


                 Limited Partnership Interests
                 (Title of Class of Securities)


                         Not Applicable
                         (CUSIP Number)


                         L. Paul Latham
                   Southwest Royalties, Inc.
                   6 Desta Drive, Suite 6500
                   Midland, Texas 79705-5510
                         (432) 682-6324
                (Name, Address and Telephone Number of Person
       Authorized to Receive Notices and Communications)


                         June 30, 2006
    (Date of Event which Requires Filing of this Statement)


If the filing person has previously filed a statement on Schedule
13G  to  report  the  acquisition that is  the  subject  of  this
Schedule  13D,  and is filing this schedule because  of  240.13d-
1(e), 240.13d-1(f) or 240.13d-1(g), check the following box:  ?






                    CUSIP No. Not Applicable

 (1) Names of Reporting Persons              Southwest Royalties,
Inc.

 (2) Check the Appropriate Box               (a)
     if a Member of a Group                  (b)  X

 (3) SEC Use Only

 (4) Source of Funds                         WC

 (5) Check if Disclosure of Legal
     Proceedings is Required
     Pursuant to Items 2(d) or 2(e)          Not Applicable

 (6) Citizenship or Place of
     Organization                       Delaware corporation


Number  of  Shares/Units  Beneficially Owned  by  Each  Reporting
Person With:


 (7) Sole Voting Power                  373.1 Units

 (8) Share Voting Power                 None

 (9) Sole Dispositive Power                  373.1 Units

(10) Shared Dispositive Power           None

(11) Aggregate Amount Beneficially
     Owned by Each Reporting Person          373.1 Units

(12) Check if the Aggregate Amount
     in Row (11) Excludes Certain
     Shares                             Not Applicable

(13) Percent of Class Represented
     by Amount in Row (11)                   6.2% of class of
                                        5,983 Units

                                             (14) Type of Reporting
                                         Person                CO
                                         (Managing        General
                                         Partner of Issuer)



Item 1.                                 Type     of     Security:
                                        Limited       Partnership
                                        Interests ("Units")

                                             Name of Issuer:
                                        Southwest Royalties
                                        Institutional Income Fund
                                        X-C, L.P.

          Address of Issuer's           6 Desta Drive
          Principal Executive           Suite 6500
          Offices:                      Midland, Texas 79705

Item 2(a).     Name of Person
          Filing:                       Southwest Royalties, Inc.

Item  2(b).     Address of Principal               6 Desta Drive,
Suite 6500
          Business Office:                   Midland, Texas 79705

Item 2(c).     Present Occupation:           Not Applicable

Item 2(d).     Criminal Convictions:              None

Item 2(e).     Civil Securities Laws
          Injunctions or
          Prohibitions:                 None

Item 2(f).     Citizenship:                  Delaware, U.S.A.

Item 3.                                 Source      of     Funds:
                                        Working  capital  of  the
                                        Reporting Person.

Item 4.   Purpose of Transactions:

     Satisfied requirements of the Right of Presentment contained
     in the Issuer's Agreement of Limited Partnership whereby the
     Reporting  Person,  as Managing General Partner,  agrees  to
     acquire Units from limited partners seeking an exit from the
     Issuer at a formula price.


Item 5.        Interest in Securities

     The  Reporting Person, which is the Issuer: Managing General
     Partner  of  the  Issuer, holds a total of  373.1  Units  of
     limited partnership interests over which it has sole  voting
     and  dispositive powers.  These Units represent 6.2% of  the
     total  5,983  Units, which are issued and outstanding.   The
     purchase transactions which resulted in the ownership of the
     Reporting Person increasing from 5% to 6.2% occurred between
     October 1, 2005 and June 30, 2006 when the Reporting  Person
     purchased  an additional 59.7 Units as part of the  Issuer's
     Right  of  Presentment program.  The price per  unit  ranged
     from $174.67 to $189.69.

Item 6.   Contracts, Arrangements,
          Undertakings or Relationships
          with Respect to Securities of
          the Issuer:                             Not Applicable

Item 7.   Material to Be Filed as
          Exhibits:                          Not Applicable



                           SIGNATURE


     After reasonable inquiry and to the best of my knowledge and
belief,  I  certify  that  the  information  set  forth  in  this
statement is true, complete and correct.





Date: July 10, 2006           By:  /s/ L. Paul Latham
                              ----------------------------------
                              L. Paul Latham, President and
                              Chief Executive Officer,
                              of Southwest Royalties, Inc.
                              the Managing General Partner