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                                                                   EXHIBIT (10a)


                              AMENDMENT NUMBER ONE
                             TO EMPLOYMENT AGREEMENT
                             DATED DECEMBER 15, 1999


         THIS IS AMENDMENT NUMBER ONE to the Employment Agreement entered into
between Yellow Corporation, a Delaware Corporation ('"Yellow") and William D.
Zollars (the "Executive") on the 15th day of December, 1999.

         1.  Paragraph 4(d) of said Employment Agreement is hereby amended in
             its entirety to read as follows:

             (d)  Supplemental Retirement Benefits. Yellow shall provide
                  Executive with Supplemental Retirement Benefits in accordance
                  with this subsection (d) and Appendix A pursuant to which the
                  Executive shall receive from Yellow upon his termination of
                  employment with Yellow (and subject to the vesting provision
                  hereinafter set forth), the difference between (i) the monthly
                  benefit that he would have received under Section 4.4 of the
                  Yellow Freight Office, Clerical, Sales and Supervisory
                  Personnel Pension Plan (the "Pension Plan") (calculated as a
                  single life annuity payable commencing at his initial Normal
                  Retirement Date as defined under the Pension Plan with an
                  actuarial reduction if payment commences prior to his Normal
                  Retirement Date) using 20 years of Credit Service as defined
                  in the Pension Plan plus his actual Credit Service credited
                  under the Pension Plan after five (5) years from September 6,
                  1996, the date of Executive's commencement


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                  of employment with Yellow's subsidiary, Yellow Freight System,
                  Inc., and using compensation as defined in Section 2.1(h)2 of
                  the Pension Plan, including Compensation previously earned
                  during his employment with Yellow Freight System, Inc. from
                  September 6, 1996 through November 7, 1999, but without any
                  reduction under Section 401(a)(17) of the Internal Revenue
                  Code of 1986, as amended (the "Code") and (ii) the monthly
                  benefit actually payable to the Executive under Section 4.4 of
                  the Pension Plan, calculated at the time the Executive
                  commences payment of a Vested Pension under the Pension Plan,
                  if any. The Executive shall vest in the Supplemental
                  Retirement Benefit described in this subsection (d) at the
                  rate of 20% per year commencing on September 6, 1997 (so that
                  he would become 100% vested on September 6, 2001), provided,
                  however, that the Executive shall forfeit any unvested portion
                  in the event of the termination of his employment prior to
                  becoming 100% vested. Notwithstanding the foregoing, the
                  Executive shall immediately become 100% vested in the event of
                  the termination of his employment under circumstances
                  entitling the Executive to benefits pursuant to Section 8.
                  Following the termination of Executive's employment, the
                  Supplemental Retirement Benefit described in this subsection
                  (d) and Appendix A shall be payable monthly commencing no
                  sooner than the earliest date of Executive's eligibility to
                  receive Retirement Benefits under the Pension Plan measured
                  from his



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                  date of termination with Executive having the option of
                  deciding when to commence payments following achieving such
                  eligibility, subject to actuarial reduction for payments
                  commencing prior to Executive's Normal Retirement Date, and
                  shall continue until the Executive's death. Upon the
                  Executive's death, if at the time of his death payments had
                  already commenced under the Supplemental Retirement Benefit
                  and if he is survived by and still married to the person who
                  was his spouse on September 6, 1996, the monthly Supplemental
                  Retirement Benefit payable to the Executive during his life
                  shall continue to said surviving spouse until her death. If at
                  the time of his death, the Executive had not yet qualified for
                  payment of a Retirement Benefit under the Pension Plan, or if
                  Executive had qualified but payments had not yet commenced, if
                  he is survived by and still married to the person who was his
                  spouse on September 6, 1996, the Supplemental Retirement
                  Benefit shall be payable to said spouse no sooner than the
                  earliest date that Executive would have been eligible to
                  receive Retirement Benefits under the Pension Plan measured
                  from his date of death with said spouse having the option of
                  deciding when to commence payments following the date that
                  Executive would have achieved such eligibility, subject to
                  actuarial reduction for payments commencing prior to the date
                  that Executive would have reached his Normal Retirement Date,
                  and shall continue to said surviving spouse until her death.


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                  The Executive acknowledges that these Supplemental Retirement
                  Benefits are an element of the compensation to be paid for his
                  services and not an unfunded plan of deferred compensation
                  within the meaning of Section 201 of the Employee Retirement
                  Income Security Act, as amended.

         2.  All other provisions and conditions of the Employment Agreement
             dated December 15, 1999 remain in full force and effect.

         IN WITNESS WHEREOF, the parties have executed this Amendment Number One
to the Agreement dated December 15, 1999 on the 20th day of April, 2000.




THE EXECUTIVE:                                    YELLOW CORPORATION



/s/ William D. Zollars                       by: /s/  William F. Martin
------------------------------                  --------------------------------


                                                Attested by:


                                                /s/  Lawrence D. Berkowitz
                                                --------------------------------



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