First rule about GL auctions, ignore the description completely. I purchased one truck as non-running, it just needed a jump start and brake fluid. My other truck was listed as running, but it had all fluids drained. Once we did put fluids in and tried starting it, we found the block of the brand new engine to be cracked and oil and coolant was flowing out of it.
Before going to do the recovery try to locate someone as close to the base as possible to act as home-base. You may get very little time on the base. And you may only have one shot at the recovery, so if the truck won't run, you may not have time to come back another day to do a 2nd recovery. It depends on the attitudes at that base.
If you can afford it, have it at least towed off the base. But if you are doing it yourself, have a recovery plan in case they try to rush you off the base quickly. The first steps of the inspection should be to check the engine oil, coolant, and check the brakes. Those items will at least allow you to drive off the base and pull over if they are pushing you off the base.
If you have time at the base, go through the rest of the pre-trip inspection from the manual. Make sure you check differential, transmission, transfer case fluids. Once the truck has run and warmed up and built up air, shut it down and listen for air leaks.
Bring spare belts and all filters with you. When you get it off the base to the "home base", change all of the fuel filters. Trust me on this, my excellent-condition Deuce only had 1 fuel filter actually filtering anything because 2 of them had been improperly installed. Do a thorough inspection of the wiring, hoses, etc. Check bolts on the driveshafts! One of the trucks we picked up had the driveshaft bolts only finger tight. Check other bolts and fasteners. Check lug nuts.
Once you are off the base and on your way, stop after a few miles to check things again. Check for leaks that didn't show up before, check tire pressures, etc.
After everything we have warned you about, sit back and take a breath. Don't be scared. You have just as much chance of having problems after buying a car from a used car dealer. Trust me, I'm a mechanic and did state safety inspections, and I've seen just as many dangerous vehicles come out of a used car dealer, and the people buying those had no clue and thought they had gems. At least you'll be going in prepared for the worse.
Jim