-Great Mileage (15-20MPG easily achievable)
-Good solid torque
-Readily Available parts and a burgeoning aftermarket (private businesses)
-Will tow better than any 1/2 ton gas engine
-Slow, so don't expect to be running with modded cummins,p-strokes or dmaxes.
-PMD failure (for electrical injected engines 94+) which can be fixed in various ways
-Takes lots of money to eclipse 250HP (at that point you should have nearly 450TQ anyway)
-The more power you make, the more heat to deal with, so overheating and EGT's are something to worry about.
Overall, a new fan clutch and a dmax fan should keep a good cooling system working optimally. Relocate the PMD to somewhere outside of the engine compartment on a heatsink. This along with a good set of glow plugs should give you a solid, reliable engine that can work harder than the half ton chassis can handle.