In this final rule, RSPA is amending 49 CFR '173.31(a)(5) to extend the compliance date for having vertical restraints systems on certain DOT specification tank cars from November 15, 1990 to November 15.1992. This amendment is based on the merits of petitions for reconsideration. The effect of this action is to minimize operational impacts on affected tahk car shippers and owners by providing an extended implementation period for equipping non-conforming tank cars with the required shelf couplers. RSPA is also amending 49 CFR 179.300-7(a), to restore regulatory text that was inadvertently deleted in a final rule issued tinder Docket HM-166W .(54 FR 38790; September 20,1989).