422,000 plus?
I bought this fine 98. 5 QC 3500 5 speed as a non-runner. After paying for it the seller said come get it whenever you want. He drove off and I went to work on it. Less than an hour later I was able to fool the VP44 with WD40 in the intake and drive it home. I've spent more on repairs than I paid for the truck but I still feel good about it none the less.
Repairs I've made thus far are the VP44 and lift pump, steering gear and hoses, APPS (bell crank asembly) and the ABS wheel speed sensor. I don't actually know how many miles are on the truck because the speedometer only worked at speeds above 55 when I first began driving it and then didn't work at all for several thousand miles until the sensor was replaced.
I repowered an old step van in 1991 with a 6BT and logged over 200,000 miles before retiring it. The engine is fine and waiting for its next transplant chassis. I also have two high mileage 91's(over 200,000 on speedometers,broken since '99) and my Dad's ride is an '04 3500 4 door 6speed with 44,000 miles.
Diesel all the way!