What year is your F350? The new F250/F350s with coil springs up front ride way better than the older trucks with front leaf springs.I paid 27k for a fully loaded f350 crew cab, all the bells and whistles, 80k miles 1 owner in January ib todays crazy market. From a dealer as well, so even higher price. 14.2mpg avg at 65mph, tow a house, rides pretty decent, drives like a new truck and has zero issues. I think that's a great deal compared to a 70k newer truck with 70k less miles.
I don't think you gain anything spending 10k less on much less of a truck and age also helps wear out things just that much faster. Pick your poison. You wouldn't know my truck was not brand new if you rode in it blindfolded.
Edit-Also has an electric rear locker, very nice for a hunting and camping rig.
The other thing that people say about the older trucks is that they have a lot of power. That's just not true compared to the latest generation of trucks. I've driven and towed with Dodge, Chevy, and Ford, with years ranging from the late '80s until now. The new trucks have way more power and better transmissions.
One of the best examples is how much everyone (at least around here) raves about the 7.3 Ford diesel. They are very reliable but have about half as much power as the new 6.7 Powerstroke. Towing with the two trucks isn't remotely close. And the transmissions of the '90s and early 2000s were garbage. Both Ford and Dodge were good for about 80k between replacements. Chevy didn't even have a diesel worth talking about through that time period.
With all that said, one of my favorite trucks ever was a "bulletproofed" '06 F350 King Ranch that I had lifted on 37s. It was fast and reliable and towed like crazy. The transmission didn't need anything but normal service until I traded it in with 270k miles on it. Even though it was tuned, that truck didn't have the power, torque, or ride that my 2018 has.