Well, the verdict is in: the 4JB1-T is NOT a direct bolt-in swap for the 1988 Trooper chassis (U.S. model, anyway -- AND it is possible that I've got the wrong mount brackets with my engine for this chassis). The mounts for the engine are about 1-7/8" forward of where they need to be.
The mounts themselves (the rubber isolator / bracket that goes between the steel frame perches and the engine block brackets) are very similar in design to the 4-cyl. gas mounts. There are 2 bolts that attach to the engine bracket instead of one, but the frame side - with the two holes spaced ~5" apart - is the same.
So, the diesel mounts will bolt to the frame. I just need to fabricate some new engine block brackets. Shouldn't be too hard, as I've got the diesel engine and gas engine to measure from. The diesel also has extra holes in the block, I assume to facilitate mounting in other applications, that I can use for the new brackets.

Right now, the project is held up a bit by the 3 crossmember bolts that have broken off in the frame. So far, I've broken a drill bit off in one and an extractor is broken off in another. I'm trying to weld some nuts onto them so I can thread them out (after generous application of heat, of course). Any suggestions welcomed!

Also, I think I've secured a good used C223 radiator to use. Hopefully it will work - should save me some cash. Looks like I'll be spending some on setting up a miniature metal shop to make the mounts. I think a bandsaw, drill press, bench grinder and bench vise will suffice...

More later ...

EDIT: Aug. 4 2005 Not so sure this sucker won't bolt right in ...

Read more recent posts for the REAL verdict!