How do you fix leaks from transfer case 242 J?

Break out the tools and crack open the case with a flat bladed screwdriver and a ball peen hammer, make sure you drain it first (30mm), they're are 11 - 15mm case bolts. Spread your gasket maker over the slightly cracked opening which you have to try and do without getting gasket sealer all over the internals. Focus and concentration in the cramped workspace coupled with a good technique may work out. Then you have to bolt it back together and wait while the seal sets-up before you refill it with gear oil, this'll give you time to pray it still works.

Your other option is to pull out the transfer case and take it to a shop and have it professionally rebuilt for around 6 bills. The shop will replace the seals and the other wearables in the unit and it'll come with a warranty.

Or spend your afternoons whiling them away wandering the salvage yard landscape for a non leaking unit, Happy Trails!