My biggest concern is whether it would pass an emission test. Say, if you put a 1985 Mercedes diesel into a 1995 Wrangler, it would probably be a no go.
The ideal diesel would be hard to find. You've got to find the right combination of performance, weight, and reliability. Most of the good ones are in heavy duty trucks, and just too heavy to be practical IMO. Most of the mewer ones are too complex. The good little ones from outside the USA could be an emissions nightmare.
2013 Wrangler JK, 285hp, NSG-370 6-speed, NV241 TC, Dana-44R/30F 3.73 axles, Rubicon suspension, armored, and Toyo Open Country ATII's...
"Too many times, too many times, paying the price just for the thrill" - Tesla