It's more work than it's worth, Just get a trans that will bolt up to the cummings.
Buy a newer 48RH, not the weak 46 RH or whatever the proper name and numbers are for later and better 4 speed O.D. trannies for the Cummins 5.9 engines.
I bought a new 1998 1/2 24 valve 5.9 Cummins powered 3/4 ton Ram 2500 with the weaker 46RH tranny in it.
I got it hot once towing my 24 Ft enclosed race car trailer with my old pump gas Duster in it in the summer in the Mojave desert and had troubles with it shifting automatically for a while after that.
I sold that truck it in 2006 and bought a new Ram 3500 4x4 for the snow up here and it has the newer better 48 RH in it, according to the mechanics at our local Dodge dealer it is a lot better than the older 46 trannies where
