There are not many options for a truck because of the input shaft length and the mounting arangment for the engine and transmission. The input shaft will either need to be as long as the 3 speed so that you can modify the bellhousing to mount the transmission directly or it will need to be longer by maybe 3/4" - 1" so that you can make an adapter plate.
Unless you just need the nostalgia of a 4 spd, get a 5 speed. The work and cost to install will be about the same and you will get overdrive. If you want, you can use a 4spd shift knob

A quick way to evaluate the condition of the transmission is to wiggle the input shaft. A fresh, or very low mileage unit should not move any amount you can notice by hand. Generally good condition, with some mileage may wiggle slightly. If it just flip flops around, it's worth maybe a little more than scrap value depending on exactly what it is.
Of course, if you can look at the gears, do it but this can help you determine if you even want to bother with removing the cover for a look.
If it is freshly painted, be cautious. Don't believe any rebuild claims without documentation or a reputation / credentials to back that person up.
Lawrenceville, GA