you looking for a 1st/second gen??
what type of intended use are you looking to do with an engine swap in mind?
what type of engine...decent power v8? small diesel?? 4.0 from last truck??
if you want an older model, and plan a v8 for 4 wheeling with some bigger tires, go with a efi swap and a 2wd truck. swap in a set of fullsize straight axles of some sort.
cheapest/easiest power per dollar likely an ls 5.3 setup with a 14 bolt/10 bolt-dana leaf sprung combination. it would net a venerable setup
if you have a nice 4.0 you want to find a home for, you will atleast want a d35 equipped truck.....so finding a stock 4.0 truck with a blown engine is the best choice...and that will be a gen 2 truck in most cases.
its much harder to find cost effective trucks in good shape...they race them out west and a decent truck....even an 84 model in 2wd you can drive home goes 2 grand or so.
the time of the nice 500 dollar trucks falling out of the sky seems to have passed....