Gas v-8's got the 46RE, no matter what weight rating truck.

V-10 and diesels got the 47, and later the 48. The 46RE will not bolt up to the v-10, or the oil burner, bellhousing bolt pattern is different.

 

I personally never seen a 46RE in a diesel, but when buying parts you have to clarify gas or diesel for the 46 as well as the 47 or 48. I don't know if that's just because the 47 internals can be used in the 46 case or because they acctually used them in both aplications at some point.

Either way, doesn't matter much to me. If you really want to know,look for the ID numbers on the flat just above the top of the pan flange below the range selector.

 

I wonder if that isn't just a product of the software the parts stores use for lookup..... The 46 trans are crap behind the V-8s, I would hate to think what a diesel, or 8.0 liter would do to them..... would need to own stock in a rebuilding company.