About the only "simple" swap that I know of is another Isuzu 3.2L, 96 or 97 vintage. Even another Isuzu motor from other years will require entirely new wiring, sensors, and computers. Any other brand motor would require all of that as well as custom fabricating mounts, exhaust, etc., even if you can get the tranny to match up...more likely you would need to swap the tranny too.

And, as Jim says, the Toyota motor isn't any more powerful than the Isuzu motor you have now.

Steve Carlson - 95 Trooper LS expo rig
Serenity now!