<PAGE>   1
                                                                    Exhibit 3.21



                          1997 AMENDMENT NO. 2 TO THE
                      THIRD AMENDED AND RESTATED BYLAWS OF
                              TCC INDUSTRIES, INC.

       Sections 2.03 and 9.01 of the Third Amended and Restated Bylaws, as
amended, of TCC Industries, Inc., a Texas Corporation (the "Corporation") were
amended at a board meeting held May 6, 1997, by deleting such provisions and
inserting the following:

       "2.03 Special Meetings. Special Meetings of the shareholders may be
called by the chairman of the board, the president, the board of directors or
the holders of not less than one-tenth (1/10th) of all shares entitled to vote
at the meeting; provided that when a meeting is to be called by the holders of
not less than one-tenth (1/10th) of all shares entitled to vote at the meeting
for a purpose other than the removal of one or more directors in accordance
with these Bylaws, prior notice of such meeting and the purposes therefor must
be set forth in writing to, and timely filed with, the secretary of the
corporation.  To be considered timely, such prior notice must be delivered
either in person or by United States Certified Mail, postage prepaid, and
received at the principal executive offices of the corporation not less than
120 days nor more than 150 days before the proposed date of the special meeting
of shareholders.  Business transacted at any special meeting shall be confined
to the purposes stated in the prior notice provided to the secretary of the
corporation and in the notice of the meeting provided to shareholders.  A
meeting called by the holders of not less than one-tenth (1/10th) of all shares
entitled to vote at the meeting for a purpose other than the removal of one or
more directors, may be canceled or rescheduled by the board of directors if
such meeting would occur within 60 days of the corporation's annual meeting.

       9.01 General. These Bylaws may be altered, amended or repealed, or new
bylaws may be adopted at any meeting of the board of directors at which a
quorum is present, by the affirmative vote of not less than sixty percent (60%)
of the entire board of directors, provided notice of the proposed alteration,
amendment or repeal is contained in the notice of the meeting.  The Bylaws may
also be altered, amended or repealed or new bylaws may be adopted at any
meeting of the shareholders at which a quorum is present, by the affirmative
vote of the holders of a majority of the shares outstanding and entitled to
vote thereon, provided notice of the proposed alteration, amendment or repeal
or new bylaws is contained in the notice of the meeting.  Any action not
permitted under these Bylaws as in effect on the date of the giving of notice
of a meeting of shareholders regarding a proposal to alter, amend, repeal or
adopt new bylaws in a manner to permit such action, may not be submitted for a
vote by the shareholders at, nor may it be the subject of a prior notice of
special meeting to the secretary of the corporation pursuant to these Bylaws
prior to, the meeting at which the Bylaws are altered, amended or repealed or
new bylaws are adopted."
<PAGE>   2

       The undersigned Secretary of the Corporation hereby certifies that the
foregoing is true and correct.



                                           /s/ FRANK W. DENIUS                  
                                           -------------------------------------
                                           Frank W. Denius, Secretary