The 6.2/6.5 diesel was OK as long as you don't pull them too hard. We had a 1982 Chevy 4WD dually we used to pull a tub grinder around with. In stock form (6.2) it wouldn't pull the hat off your head, so we put on a Banks turbo. This helped somewhat but then it would overheat easily and head gaskets became a problem. We then upgraded to a 6.5, which was built for a turbo. This helped somewhat, but a Dodge 3/4 ton with a 5.9L Cummins would leave the dually in the weeds every time and burn less fuel to boot.
We had two other pickups with 6.2s in them and we got along with them OK--fair power and economy but they were nowhere near the diesel the 5.9 Cummins is.
