My .02.....A great little durable diesel that I transplanted into an S 10 once is the Olds 4.3 V-6 diesel that was available in the Cutlasses and Monte Carlos in the early eighties, usually with a 200R4 behind them. Was a great engine with all of the recent problems with the 5.7 olds diesel addressed and corrected, but the earlier problems were still to fresh, so GM shelved the project after three years of slow sales. There was actually a hi-po version GM had planned that was running loe 1/4 mile times, though I cant recall the numbers. There's info out there if you Google it.
