These trucks are known quantities. They're durable, reliable, parts are cheap, and every shop knows how to work on them. Keep ahead of the maintenance, pay close attention to anything it tries to tell you, replace the stuff that can stop you on the highway before it actually does (e.g. fuel pump, coolant tees, etc), and you'll likely never be stranded. Lots of people running around with 350K+ miles on these rigs.
I used to work on drilling rigs in the middle of nowhere Montana, NoDak, Wyoming, and learned the hard way that I was better off driving a 20 year old GM or Ford truck with a bunch of miles on it than a much newer Land Rover I couldn't get parts for anywhere.
My wife and I are finally at places in our careers where we make good money, but we want to retire when we're 60. That means no brand new cars or trucks, and keeping the ones we have tip top. If you can do the work yourself, buy second hand trucks and keep them reliable, you'll save literally hundreds of thousands of dollars over your lifetime.