I've never messed with a JTruck tank, so hard to say? They're a different animal than the wags/cherokee tanks.
Guessing a GM pump could be stuffed in there without too much trouble though. Something from an LS car or truck maybe?
I like the fact that if I ever did have an issue with either of mine, any parts store likely has the pump on the shelf, or another store close by does.
They're MUCH cheaper than aftermarket too.
My '88 has a GM truck pump stuffed in there, and there are smaller(newer model) units out there.
If I can stuff an LT1 pump assembly in a boat tank lol, I'm sure finding something that'd work in a JTruck tank wouldn't be too bad.