what is wrong with your current starter? if you got the factory style starter for your truck they are usually fairly easy to repair. usually the 1 contact in the solenoid wears out causing the starter to be hard to start or not start at all.
on my spare starter i used a rubber washer to shim the contact. as you can see it was almost worn down to nothing.
from 88 on they switch to a smaller starter. you can still run the older style starter which are pretty much indestructible and rarely wear out but they are heavier and more of a pain in the ass to install or swap out. you can take the starter off a 2nd gen but make sure you grab the connector and as much of the starter wire as possible. a 2nd gen starter should be similar to what is one your truck except for some of the really new 2nd gens had plug in connectors on the starter. if you can get one off a 91-98 ram truck or van it would be the one that works best. i think you might need to swap over the little adapter from your old one to the new but it just bolts onto the terminals. also shouldn't matter whether it is a v6 or v8. they both use the same starters
starter off a 87 and older on the left 89 in the middle and 91 to the right