The size of the chassis side bolt holes and the spacing on the bolt holes for the swaybar may be different, I can't remember for sure. I know there were differences between my '79 and '00 but not sure if the '91 and '79 are the same or not.
'00 Atlantic Blue GT - '03 Cobra swap, TKO600, full MM suspension
'01 Corvette - D1 blown stroker
'85 Mustang GT - bone stock except exhaust