off the top of my head from what ive read its a straight swap and same gearing. TX10 transfer case, pre 03/02 is what you want. After 02/03 they narrowed the transfer chain. According to pirate the older tx10 is good for 40" tyres.
bit stumped with what to do about the gearbox mount... front driveshaft will get in the way of using the factory mounts, so i was thinking of a roc ring type thing for the rear of the transfer case but the crossmember for the lower links is going to be in the way...