My dads worked on them lots and hates the 6.2s, he says he thinks they were based off a chev 350 and were horrible engines. Not to say others havent had luck with them, but hes been around the block plenty of times and does not like them. Underpowered and self destructive. I wouldnt get one if it were me.
Kaliburz, I thought the 6.2 was the early v-8 diesel gm made???
I dont know anything about the 6.5s though...