There’s nothing in the transfer case you can’t work on.
HOWEVER! Where’s the leak happening? If it’s just out the rear where the driveshaft goes, you can pull off the rear output shaft housing, and replace the bushing that supports the driveshaft, and the rear seal… there’s a nice rear seal out there that has an accordion boot/dust seal attached to it.
Also! When my 208 started leaking- I just swapped a 241C in. It’s a direct replacement and a hell of an upgrade. Just a hint lower gearing, stronger, and has an internal oil pump circulating the lube.
Might be getting harder to find a passenger drop 32 spline NP241 these days? Good option though. They were found in the 2500 suburbans 1987-91 behind the 465, and also the 400 automatics (with different adapter)