Camaro/Firebird NEW GM for 4L60E Transmission Adapter Kit for Gen I & II Engine Installation. GM Performance Parts is pleased to announce the availability of a new transmission kit that will allow a Gen III/IV 4L60E or 4L65E transmission to be installed with a Gen I & II style engine. This kit includes a spacer ring, shims, dowels, bolts and flexplate. This kit will only work with a one piece rear main seal engine. Shipping is not included.