Polyurethane bush set for rear subframe trunions. Cars manufactured before 1976 use the same bush C-STR638, at the front and rear of the subframe, 8 bushes per car in total. Starting in 1976 (MKIV) the front trunion bush was enlarged, that bush C-STR639 is now available in Poly also. MK4 on cars will require 1 set of C-STR638 and 1 set of C-STR639