The 8 1/4 thread

Actually I have never heard of different offset housings, only the carrier. It is just like the spacer for the Chevy rears where you shim out the ring gear instead of changing carriers. They used to make the spacer kit for the 8.25 and Dana I believe which also came with longer special bolts. The issue with using Dakota carriers is mid 96 and up have different spline count and some need different carrier bearings.