When I bought my '69 K5 Blazer the guy I bought it from said it should be good to go but would need a little tinkering as it had been sitting for about four years. I had planned to drive it from Corpus Christi, TX back to Houston where I lived at the time. It needed a battery and a fuel pump to get it running in his back yard. Realized that only the head lights were working, no other bulbs on the truck would illuminate. Got it out on the street and realized that only the front left brake would work. When you step on the brakes it would hard-left into oncoming traffic. The fuel gauge showed empty so I took it to a gas station and tried to fill it up. It clicked off after only a gallon or two but I did not think anything of it. It promptly ran out of gas about 10 miles away, confirmed by dropping the tank on the side of the highway. A quick trip to another gas station for gas cans and I dropped that thing back off and trailered it home another day. I later found that the water neck was corroded through, the radiator was plugged, the accelerator pump on the carb was blown, all the shocks were blown, one rear wheel cylinder was blown, the other seized, the right front wheel cylinder was seized, the shifter linkage was sticking, the horn did not work, the reverse lights did not work, it had shorts in the electricals making the battery die, etc. An amazing amount of crap...and I fixed it all!
