Welcome. I'm pretty sure all the tranny internals are very similar, but the bell housing are all different. My S10 Chevy with 4.3 v6 has the same tranny as the trooper as well, but it's different as well so I'm betting it won't be a drop in for you. GM had a concept tracker that had a 4.3 v6 stuffed in a 2door soft top tracker so anything can be done, but it will be custom. What mods are you doing to your tracker? I had a sidekick once. If it was not too small I would still have it cause it was a great truck. Some pics of it: http://www.conman.8k.com/ warning pop-up ads on this site cause it's a free hosting place. Sorry.
Good Luck,
Con
Good Luck,
Con