I am looking to buy a 8.1. I am looking at a 2002 with the alison trany, with 133,000 miles on it. It looks clean and sounds like it was maintained well. It does have a fifth wheel ball in the back so I am sure it has pulled some. How many miles are these 8.1's good for?
Thanks

That's all relative. If it's well maintained from the start there's no reason not to exceed 250k. If it's been neglected in any way, who knows? The real question is how long can you keep filling the gas tank?

You should be fine, the 8.1 is put into RVs and HD trucks, it can pull a fifth wheel fine. Just keep maintaining it and it will last. The Allison is what's great, they last forever, the engine will go before the tranny and that should be 200k plus.