Whoa nellie, 2K? Buy the whole thing for chrissakes.
You need to find out if the truck its on is 4wd or 2wd. The GV will swap over with the right parts, but you have to remember, the GV bolts onto the back of the transfer case. The '85 has the BW1345 while the' 88 has the BW1356. I don't know what the difference is between the tail housings on those 2 TC's, but i'd be surprised if they were the same. I would call Gear Vendor, they will be more than happy to help. If you do need a differnet adapter, last I heard from them it is around $300 with a required EXCHANGE of the adapter in your possession.
Seriously, if you have the extra scratch, use your noggin and buy the whole truck. With the intercooler and the turbo, you won't have any problems getting your money back. Just remember to offer 'em here first.