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                                                                    EXHIBIT 5(b)

                       NEAL, GERBER & EISENBERG LETTERHEAD


                                  May 17, 2000

Union Tank Car Company
225 West Washington Street
Chicago, Illinois  60606

         Re:  Registration of Pass Through Certificates

Ladies and Gentlemen:

         We have acted as counsel to you in connection with the filing by Union
Tank Car Company, a Delaware corporation (the "Company"), of its Registration
Statement on Form S-3 (the "Registration Statement") under the Securities Act of
1933, which Registration Statement, together with a registration statement
previously filed by the Company (Registration No. 333-45105), relates to up to
$302,148,000 in aggregate principal amount of Pass Through Certificates of the
Company (the "Certificates"). The Certificates will be issued pursuant to the
terms of the Pass Through Trust Agreement dated as of May 17, 2000, to be
entered into between the Company and Bank One, National Association, as Pass
Through Trustee (the "Pass Through Trustee"), the form of which has been filed
as an exhibit to the Registration Statement (the "Pass Through Trust
Agreement"), as it may be supplemented from time to time by a separate
supplement for each series of Certificates (each, a "Supplement").

         As such counsel, we have examined the proposed form of the Pass Through
Trust Agreement and such other papers, documents and certificates of public
officials and certificates of officers of the Company as we have deemed relevant
and necessary as a basis for the opinions hereinafter expressed. In such
examinations, we have assumed the genuineness of all signatures and the
authenticity of all documents submitted to us as originals and the conformity to
original documents of all documents submitted to us as conformed or photostatic
copies. We have also assumed that the Pass Through Trust Agreement will, when
executed and delivered, be substantially in the form submitted to us for
examination, that the specific terms and provisions of each series of
Certificates will be approved by or pursuant to appropriate action of the Board
of Directors of the Company and that the Supplement for each such series of
Certificates will be duly authorized, executed and delivered by the Company. As
to any facts material to our opinion, we have relied upon statements,
certificates and representations and warranties of the Company, and its
officers, including representations and warranties contained in the Pass Through
Trust Agreement.



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         Based upon and subject to the foregoing, it is our opinion that,
assuming (i) the due authorization, execution and delivery of the Pass Through
Trust Agreement and each applicable Supplement by each of the parties thereto
(other than the Company), (ii) that the Pass Through Trust Agreement and each
applicable Supplement have not been terminated, varied, transferred or assigned
and (iii) the due authorization, execution, issue, delivery and authentication
by the Pass Through Trustee of the Certificates to be issued under the Pass
Through Trust Agreement and each applicable Supplement, in each case in
accordance with the terms of the Pass Through Trust Agreement and each such
Supplement, (A) each of the Pass Through Trust Agreement and each applicable
Supplement, when duly executed and delivered, will constitute a valid and
binding agreement of each of the parties thereto, and (B) the Certificates, when
duly executed, delivered and authenticated by the Pass Through Trustee in
accordance with the terms of the Pass Through Trust Agreement and each
applicable Supplement and sold in accordance with the related purchase agreement
or underwriting agreement between the Company and the purchasers or
underwriters, as the case may be, named therein, will be validly issued, will
constitute valid and binding obligations of the Pass Through Trustee in
accordance with their respective terms and will be entitled to the benefits of
the Pass Through Trust Agreement and each applicable Supplement in accordance
with their respective terms and the terms of the Pass Through Trust Agreement
and such Supplement.

         The foregoing opinions are subject, as to enforceability, to the effect
of (1) applicable bankruptcy, insolvency, reorganization, moratorium or other
similar laws relating to or affecting enforcement of creditors' rights
generally, and (2) general principles of equity (regardless of whether such
enforceability is considered in a proceeding at law or in equity).

         We are members of the Bar of the State of Illinois, and we express no
opinion herein concerning any laws other than the law of the State of Illinois,
the Delaware General Corporation Law and the Federal law of the United States of
America.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the caption "Legal
Opinions" in the prospectus relating to the Certificates that constitutes a part
of the Registration Statement.

                                            Very truly yours,

                                            /s/ Neal, Gerber & Eisenberg

                                            NEAL, GERBER & EISENBERG