GM 3800
Toyota 1ZZ-FE 1.8L *have had two of these now put a ton of miles on them and have never had a single issue*
Nissan KA24E from the older Hard body pickups. Had a 93 and a 92 that were bulletproof and have seen them with nearly half a million miles on them. I got 300,000 on one of them and was running great when I sold it. The other one I sold with 150,000 miles and it never left me stranded.
Jeep 4.0L--Owned an early 90's model that I sold for 800 bucks after putting 400,000 miles on it. Bad fuel economy, but very reliable.