Ok, so when buying a used 4x4 truck, what are some quick things that should be checked before handing over the moola? Obvious for me is mileage, overall condition, leaks, engine sound, test drive.

like what kind of truck>

I realize some things would be specific to the type of truck.....I for one like gm/chevy stuff, I just bought a '90 gmc 2500 4x4 suburban, but I also plan on buying an older gm 4x4 pickup before too long.

cracked frame behind the steering box and crab walking indicating a tweaked frame. those are the only 2 problems I've ever had with GM trucks. Toys have a penchant for rusting where the front rear spring hanger meets the frame, especially on the passengers side. Just about any Sammi I've looked at that's been wheeled tweaks the frame rails up on the pass. side.