There is a difference. I didn't know it. My tranny bolted in fine. The four speed pins I believe may be slightly offset as to use a dial indicator to get standard bellhousing centered. Similar to this. Hopefully someone will chime in.
Quick Time RM-146 Quick Time OFFSET DOWEL PIN - 10MM, .014 Offset
I changed u joints rebuilt my rearend and all kinds of crazy stuff trying to figure it out.
