For me, What I look for is Rust. I HATE rust, sure you can patch panel or replace fenders and what not but it's work and money so why not just start with a fairly rust free one to begin with. Next would be looking for shody fab work if any. I looked at a K5 once that had some of the most horrible fab work I had ever seen done to it. I allmost ran screaming from it. I just politely told the guy no thanks! and backed away quickly, very quickly. If it's a bone stock K5 then no big deal. Look for cracks or a repair around the steering box. If it has no signs of cracks or no old repair, your lucky to have found one that hasn't cracked......yet.
Look at the wireing, if it's a rats nest your probably going to have electrical issues, which can be a PITA to trouble shoot. Sure you could buy a complete aftermarket wireing harness but again more money and time lost/wasted. And if your NOT an electrical guy your in over your head trying to install a all new harness. Then look at the drive train. Look for bent/broken stuff, cracks, weld repairs.
You can usually tell if a truck has been in a wreck and the frame has been bent substantually. Again, I looked at a burb once and saw that the front frame horns were welded back on from being sheared off in a wreck. I told the guy I could tell it had been hit hard, He admitted it had been. Then he said, "boy, you sure know what to look for", I passed on that burb too.
If you can pull the carpet up, look for rust in the floor board. If it smells Musty or mildewy inside. Check the weather stripping. Ofcourse your looking at an OLD rig so this stuff can't be expected to be perfect. It's a matter of what your willing to accept as far as condition goes. If it has been converted to 1 tons, look at the quality of the install itself. You can usually tell a quality install from a crappy one. Look for huge lift blocks and crappy stuff like that, and stay away from it. If it's a D60/14FF converted truck you might want to overlook some things. 1 tons ain't cheap, atleast not a D60.
Heavy rust, Wrecked, Very bad wireing IF I'm looking for a DD is a absolute pass for me. Now if your looking for a Project truck, you can be more laxed on SOME things like wireing. I AM doing a complete new Wireing harness, My truck is a total project truck, although it would be considered a very rust free 73' K5. Light surface rust does not count as rust in my book. Bad rust is ofcourse deep pitted metal or Swiss Cheese metal.
I have rambled on long enough, now go buy a K5 would ya!.
