EXHIBIT 24.3

                                POWER OF ATTORNEY

         The undersigned  members of the Employee Benefits Committee of Ultramar
Diamond Shamrock  Corporation (the  "Committee")  hereby  constitute and appoint
Timothy J. Fretthold and Todd Walker,  or either of them, as the true and lawful
attorneys-in-fact  and  agents  of the  undersigned,  each  with  full  power of
substitution  and  resubstitution,  to do any and all acts and  things  in their
names and in their  respective  capacities as a member of the Committee,  and to
execute any and all  instruments  for them and in their names in the  capacities
indicated above, which said attorneys-in-fact and agents, or either of them, may
deem  necessary  or  advisable  to  enable  the  Committee  to  comply  with the
Securities Act of 1933, as amended, and any rules, regulations, and requirements
of the  Securities  and Exchange  Commission in connection  with a  Registration
Statement on Form S-8,  including without limitation power and authority to sign
for them, in their name in the capacities  indicated  above,  such  Registration
Statement  and any  and all  amendments  (including  post-effective  amendments)
thereto, and to file the same, with all exhibits thereto, and other documents in
connection  therewith,  with the  Securities  and  Exchange  Commission,  hereby
ratifying and  confirming  all that the said  attorneys-in-fact  and agents,  or
their  substitute or  substitutes,  or any one of them,  shall do or cause to be
done by virtue hereof.

/s/ Timothy J. Fretthold
    Timothy J. Fretthold

/s/ Penelope Viteo
    Penelope Viteo

/s/ Lorraine Racicot
    Lorraine Racicot

/s/ Steve Blank
    Steve Blank

Dated: October 3, 2000