Here's what I've gathered over the last few weeks since I believe my transfer case needs to be replaced as well:
The TOD system is actually part of the transfer case. Inside the t-case live electromagnetic clutches that are the heart of the TOD system.
The only other Isuzu transfer case that was equipped with TOD to my knowledge were in top-trim 99-05 Troopers with automatic transmissions. Supposedly, these also came with a 2-hi option, but I don't know how that affects its usage in a VX. Other than that, the Trooper t-case was equipped with higher low-range gears. The transfer case is otherwise a bolt-in replacement.
Rodeos w/manual transmissions have the transfer case built into the MUA5, and is non-removable. I don't have any information on Rodeos with automatics, but there is a possibility you may be able to use its transfer case, albeit you will lose TOD.