How about a Bellhousing Adapter from AMC 327 to Gen3 AMC or maybe even a Chevrolet or BOPC.
I understand there are too few tranny choices for the 327.
Sounds like a simple product to build.

As a lot of these rigs came with 3 speeds and the only 4 four speed that I am aware of is the T98.

Wouldn't be nice to pick up a cheap NV3550 and transfercase and bolt it in behind a 327 for your older Gladiator truck?