SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549



                                  SCHEDULE 13G/A
                                (AMENDMENT NO. 4)

                    UNDER THE SECURITIES EXCHANGE ACT OF 1934


                              QUANTA SERVICES, INC.
             ------------------------------------------------------
                                 (NAME OF ISSUER)


                    COMMON STOCK, $.00001 PAR VALUE PER SHARE
             ------------------------------------------------------
                          (TITLE OF CLASS OF SECURITIES)


                                    74762E102
             ------------------------------------------------------
                                 (CUSIP NUMBER)

     Check the  appropriate  box to  designate  the rule  pursuant to which this
Schedule is filed:

[X]  Rule 13d-1(b)

[ ]  Rule 13d-1(c)

[ ]  Rule 13d-1(d)


The  remainder  of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
notes).





- ------------------------------------------------------------------------------
  1   NAME OF REPORTING PERSONS
      S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS

      THIRD AVENUE MANAGEMENT LLC

      (EIN 01-0690900)

- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
  2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
       (a)  [  ]
       (b)  [  ]
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
  3   SEC USE ONLY

- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
  4   CITIZENSHIP OR PLACE OF ORGANIZATION

      DELAWARE LIMITED LIABILITY COMPANY

- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
                   5 SOLE VOTING POWER

                           6,652,200
   NUMBER OF     ---------------------------------------------------------------
                 ---------------------------------------------------------------
     SHARES        6  SHARED VOTING POWER
  BENEFICIALLY
    OWNED BY               NONE
                 ---------------------------------------------------------------
                 ---------------------------------------------------------------
      EACH         7  SOLE DISPOSITIVE POWER
   REPORTING
     PERSON               7,117,900

                 ---------------------------------------------------------------
                 ---------------------------------------------------------------
      WITH        8   SHARED DISPOSITIVE POWER

                           NONE
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
 9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING
      PERSON

           7,117,900
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
 10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
      CERTAIN SHARES*
             [    ]

- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
 11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

           6.1%
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
 12   TYPE OF REPORTING PERSON*

           IA
- ------------------------------------------------------------------------------

ITEM 1.

     (A) NAME OF ISSUER:

         Quanta Services, Inc. (the "Issuer").

     (B) ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES OR,IF NONE, RESIDENCE:

         1360 Post Oak Blvd, Suite 2100, Houston, TX 77056

ITEM 2.

     (A) NAME OF PERSON FILING:

     This schedule is being filed by Third Avenue  Management LLC ("TAM").
(TAM is sometimes referred to hereinafter as "Filer").

     (B) ADDRESS OF PRINCIPAL BUSINESS OFFICE:

     The address of the principal executive office of TAM is:
     622 Third Avenue, 32nd Floor, New York, New York 10017.

     (C) CITIZENSHIP:

     The  citizenship  or place of  organization  of the reporting  person is as
follows:

         Delaware Limited Liability Company.

     (D) TITLE OF CLASS OF SECURITIES:

         Common Stock, $.00001 par value per share.

     (E) CUSIP NUMBER:

         74762E102

ITEM 3. IF THIS  STATEMENT  IS  BEING  FILED  PURSUANT  TO  RULES  13D-1(B),  OR
13D-2(B), CHECK WHETHER THE PERSON FILING IS A:

         (E) Investment  Adviser.  TAM is registered under Section 203 of the
Investment Advisers Act Of 1940.

ITEM 4.  OWNERSHIP.

     (a) & (b) TAM beneficially  owns 7,117,900 shares, or 6.1% of the class of
securities of the issuer.

           (c)    (i) TAM: 6,652,200

                 (ii) Not applicable.

                (iii) TAM: 7,117,900

                 (iv) Not applicable.

ITEM 5.  OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

     If this  statement  is being  filed to report  the fact that as of the date
hereof the reporting  person has ceased to be the beneficial  owner of more than
five percent of the class of securities, check the following [ ].

ITEM 6.  OWNERSHIP  OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

     Third  Avenue  Value  Fund,  an  investment  company  registered  under the
Investment Company Act of 1940, has the right to receive dividends from, and the
proceeds  from  the  sale  of,  4,847,600  of the  shares  reported  by TAM, and
Various separately  managed  accounts for whom TAM acts as investment  advisor
have the right to receive  dividends  from, and the proceeds of the sale of
149,200 shares reported by TAM.

ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
        SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY.

         Not Applicable.

ITEM 8.  IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.

         Not applicable.

ITEM 9.  NOTICE OF DISSOLUTION OF GROUP.

         Not applicable.

ITEM 10. CERTIFICATION.

         By  signing  below I  certify  that,  to the best of my  knowledge  and
belief, the securities referred to above were acquired in the ordinary course of
business  and were not acquired for the purpose of and do not have the effect of
changing or  influencing  the control of the issuer of such  securities and were
not acquired in connection  with or as a participant in any  transaction  having
such purposes or effect.


                                    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.

                            February 9, 2004
                         ---------------------------
                            (Date)




                         THIRD AVENUE MANAGEMENT LLC

                         BY:/S/ MARTIN J. WHITMAN
                            ------------------------
                            Martin J. Whitman
                            Chairman and Co-Chief Investment Officer