I don't know the specific model # of the engine, but it's an 86 Trooper turbo diesel, so whatever was available that year in 4 cyl. diesel if that's of any help.
Maybe someone more familiar than I will chime in with any swapability issues.
I wasn't kidding about less than 50 HP, it's comfortable cruising speed is 60-65. On the other hand, my friend that owns it gets a little nervous when anywhere near the redline.(about 3500 RPM iirc)