Isuzu:
2.8 - superb lump, but getting rare; also expensive to fix 30+mpg
3.1 - doesn't like poor cooling, not as tough as the 2.8
3.9 - rare but awesome, try to get it with OE exhaust brake
Daihatsu 2.8 - okay. low on rev, loads of grunt, poor fuel economy - needs a 'cooler