I guess I get to be the high milage champ for now
My '03 dually has 86k miles on it. The truck works for a living being hooked to an 8000lb (empty) gooseneck 99% of the time. Daily loads get up to 15k pretty easily. The truck and trans are totally stock and no problems so far. My '03 QC is on a similar trailer 90% of the time and has just over 70k miles on it now. Totally stock and no problems with that one either.
I've been pleased enough with them to get one for myself. The '05 replaced an '03 Chev Duramax Allison truck that turned its transmission fluid black three times in 5k miles (between 25k and 30k) with very little light towing. GM said it was normal, I don't think so, down the road it went.

I've been pleased enough with them to get one for myself. The '05 replaced an '03 Chev Duramax Allison truck that turned its transmission fluid black three times in 5k miles (between 25k and 30k) with very little light towing. GM said it was normal, I don't think so, down the road it went.