The 88 Isuzu's had 4cyl Isuzu motors (I had one for 13 years), and if I recall correctly, also could be had with the 2.8 liter V6 that GM put in a bunch of different vehicles. I am talking Troopers (SUV's), not pickups. They were badged with a "V6" badge on the back right-hand side of the doors. This may have started in 89, but somewhere in there they had the GM V6's for several years until they restyled the Trooper and Isuzu made or sourced a DOHC V6 for them.
Whether or not the transmissions and engines all had a Chevy bolt-pattern, I have no idea, but I do know they had the GM 2.8 motors for several years.
Oh, GM and Isuzu are still cozy as the original Duramax diesel in GM's heavy duty trucks is an Isuzu designed motor. I think Isuzu may have produced the motors when they first came out, but I don't know if that is still true.
