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                                                                     EXHIBIT 5.1
 
                              MISICK AND STANBROOK
                                  P.O. Box 127
                                Town Center Mall
                                 Providencioles
                             Turks & Caicos Islands
                              British West Indies
 
February   , 1994
 
USX Corporation
600 Grant Street
Pittsburgh, PA 15219-4776
 
USX Capital LLC
c/o USX Capital Management Company
    5555 San Felipe Road
    Houston, Texas 77056
 
Gentlemen:
 
     We have acted as Turks & Caicos Islands counsel for USX Corporation ("USX")
and USX Capital LLC (the "Company") in connection with the proposed issuance and
sale by the Company of up to 10,000,000 of the Company's Cumulative Guaranteed
Monthly Income Preferred Shares and the Guarantees of such Preferred Shares by
USX.
 
     We have participated in the preparation of the Registration Statement on
Form S-3 with respect to said Preferred Shares and Guarantees to be filed with
the Securities and Exchange Commission.
 
     Based on the foregoing, we are of the opinion that USX Capital LLC has been
duly incorporated and is validly existing and in good standing under the laws of
Turks and Caicos Islands. We are further of the opinion that, when the Preferred
Shares are issued by the Company, and sold, said Preferred Shares will be
legally issued, valid and binding obligations of the Company.
 
     We hereby confirm our opinion as set forth under the caption "TAXATION" in
the Prospectus constituting part of the Company's and USX's Registration
Statement on Form S-3.
 
     We hereby consent to the use of our name, including under the captions
"TAXATION" and "VALIDITY OF SECURITIES", in the Prospectus constituting part of
the Form S-3 Registration Statement of the Company and USX relating to the
Preferred Shares of the Company guaranteed to the extent set forth in the
Prospectus by USX, and to the filing of this consent as an exhibit thereto.
 
                                          MISICK AND STANBROOK