Pretty much covered above.
Look out for your wallet...
Be sure to get some shipping quotes if it's not local. Shipping heavy equipment is expensive. Period.
Expect to replace *every* piece of rubber on t he truck. Tires, cab bushings, swaybar bushings, tie rod boots. It's easy to toss 5-8 grand at rubber. And the tires on the truck will need replacement, it's a given. The date codes on the tires tell the tale and these trucks are often stored for years in harsh climates. Rubber has a shelf life, and NOS or not most of the surplus rubber sold for these trucks is ready to fall apart (even if it's new in the original package). Shop accordingly.
Electrical issues are common. You'd be wise to clean every contact between batteries, starter, power distribution. It's duel voltage alt (a couple grand to replace, btw). These trucks are know for their electrical gremlins. You can ditch the four batteries for duals (it's advised even, due to the low output alt). *some of these change with the A1R trucks (produced after 2006), but those models are rare
That annual $29 oil change jumps to about $1200 after all the fluids and filters are replaced (if you do it yourself, triple that if you just drop it off at the CAT dealership).
If you wrench your own pickup truck, you have tools. You can forget those. You need BIG tools now.
Do you live where you need air-conditioning in the cab? An OEM a/c will set you back about 4 grand just for the kit. Installing it is no simple task.
If you live where there is an HOA, you'll want to price storage for the truck. While some neighbors love them, most don't want to look at them.
Insurance can be an issue for some folks. It varies by state and even which part of a city you live in whether you can even find a policy.
Even getting the truck titled is impossible in many states. You can often get it titled as a "former military vehicle", but that's supposed to be limited use (parades, car shows, events, etc). Some states allow for commercial registration, which can sometimes require a CDL. Some states simply tell you NO. Check your local laws (not just what the guy selling the truck says and don't assume you can always replicate what he did).
Fuel cost is a consideration. You'll get 4-7 mpg with these trucks (with a 56 gal tank). What 's diesel selling for at the station down the street today? Because it will go up tomorrow. Diesel keeps crawling up and never came down like gas did (I'm paying double what I paid three years ago). And even once Brandon is gone, it will take years to rebuild the supply (and that's assuming this country makes a FULL 180 in 2024).
That's the reality and for a lot of people these are not issues. But know this going in...
They are awesome trucks, but not cheap to own or operate.