>>4788070 lb
Pulling 4K infrequently, probably gas. Frequently, diesel. How many miles depends on expected longevity of model. Some stuff is great with 250k. Others is worn out POS.
My general rule of thumb is truck 1/3 used up for 1/3 of MSRP. That’s hard to do do with economy so good after economy so bad, though. Nobody was buying trucks ten years ago, so they’re going for silly money.