Obviously where you're located they use plenty of roadway salt. Not where I'm at out in Washington state. Preventive maintenance is far more important than miles. When I was a young man, 100k miles was like way over the hill. Not so much today. However I never buy anything, car, boat, motor home used without spending an extra $100-$150 to have it checked out completely at a certified dealer. Has always been cheap insurance.
I also tend to keep rigs for quite awhile. That's sure way to maximize one's investment. Had a custom 1994 Ford Centurion 3/4 ton four door bronco that I bought after the original owner had put 30k on it. That was 1997. Sold
it in 2017, mainly because I just wanted a diesel. Only had 118k on it. Mechanically perfect. I guess my point is, if one is diligent when it comes to service, vehicles are like the energizer bunny.....just keep going.
Interesting saying about 7.3 Power stokes. Everything around them will fall
apart before that engine will. A friend of mine has a 2000 with a 7.3 that appears nearly new. Has almost 500k on it. Just recently replaced the tranny even though it was still ok.