Yes don't fall into the trap I did. The manual never mentoned the transfer case. Had I known I would have changed the fluid on the same schedule as the transmission. From what I understand this transfer case (New Process 236) uses a special fluid available only at the dealer. The original fluid was red now it is blue. Your manual will list the old part number. Expect to pay about $7.00 a quart or more you will need 3 quarts.
I got 96,000 on my Jimmy with the auto 4WD and now the thing is stuck in 2HI. I never serviced the transfer case even though the truck was dealer serviced every 3000 miles! The dealer never mentioned the transfer case and its not in the manual. I followed the heavy duty maintenance schedule to the letter. They wanted to clean my spark plugs every 36,000 though and thats not in the manual either!