Since the engine and transmission were out of a 2WD ’94, the tail end of the transmission had a four-bolt square pattern. Level 10 had the parts on hand to get us into a six-bolt pattern case at the same time they installed the Advance Adapters mainshaft and did the performance rebuild. Then we used an Advance Adapters ultra-short 1.25-inch adapter (PN 50-9305) that worked with whatever six-bolt, 23-spline-input T-case we went with. It provides for a VSS sensor leaving the Atlas tailhousing free for a speedometer. The kit comes with a transmission-mount foot that is threaded to accept a typical GM transmission mount (Advance Adapters PN 716654).