 Heads featured new raised lip for improved valve cover sealing and the two center intake bolts were changed from 90-degree orientation to 72 degrees.G92 and L98 cars got the Borg-Warner HD four pinion rear end, produced for GM's Holden of Australia (Firebird WS6 cars went to this unit in 1986).These units can be identified by their 9 bolt (rather than 10) differential cover that has a rubber drain plug.