Ugh, there's work to be done.
So you may or may not know my VX. It has been highly modified over the years to include the AR5 5 speed conversion and I ditched the TOD in favor of a manual 2hi, 4hi, 4lo transfer case from the mid '90s Rodeo. This allows for the revolution 3:1 gear reduction mod to achieve a much better final crawl ratio. Unfortunately this TC is now popping out of 4lo to the point I can barely even hold it in gear with a strap and all my strength together. I've got another TC on the way and plan to swap the revo gears into that one. This should fix the issue until I wear out the replacement TC.
This has put me on a mission though to find a better solution. The two options I'm pondering are:

1) Hummer H3 manual trans mated to the NR6 - Borg Warner 4494 = 4.01:1 low range transfer case. This I think would work likely without changing the bell housing but that's easily done if needed. I think the input shaft dimensions are the same as the AR5. I would need to get the H3 transfer case control module for switching between 4hi and 4lo or wire another solution for controlling the TC shift motor. Unknown is the clutch and flywheel compatibility.
Pros: Good source though small numbers of later model transmissions. Robust 4:1 TC option with planetary gearing. Likely bolt on at the input side.
Cons: The 4:1 TC option is more limited hence more expensive. TC has a weak nylon internal shifter fork in the ~2009 and older cases that needs to be upgraded to an aluminum one, output side will need custom drive and prop shafts created.

2) Jeep AX15 five speed mated with a flipped NP231 or more likely a Dana D300 TC. Input shaft is shorter on the AX15 so extended pilot bearing would need to be sourced and possibly machined. Unknown is the clutch and flywheel compatibility.
Pros: Lots of part to choose from. Lots of aftermarket products available. Fully mechanical shifter setup. 4:1 TC gearing also available. Mating options for TC well sorted out and supported.
Cons: More customization necessary since the input side will need to be custom too. Output side will need custom drive and prop shafts created although more support available for this than with the H3 setup.

I'm sure there's more things that I haven't though of yet and problems I'll run into but I think it's worth the effort. I'm really leaning towards the H3 AR5/NR6.