I have the 8.3 in a 93 Safari here in NZ Motor runs like a dream and has never missed a beat. Our legal limit for this size unit is 90kph (56 miles per hour)and with the Allison 6 speed gearbox we are normally doing about 1600rpm for the limit. I pull a Ford Courier utility as my toad, and the engine has no problem sticking at the limit even on long climbs.