If you were wanting to flip them, you'd have to get on a Van Lifer FB page. They will certainly get on a plane or ride with someone to pick up the right vehicle.
Mileage isn't the half of it. See how to get in the ECM and find the engine hours. The ambulance co that I towed for, used Ford F550's for their trucks. It was very common they got new crate engines at 50,000-60,000 miles. This is due to all the idle time. Their trucks are usually running 24/7 staged all over the OKC Metro area. They are only driven when running to a call and then to a hospital, then back to the truck barn for shift change and getting restocked with IV's, gauze, maskes, gloves etc and then back out at their post. It was usally between 15,000 and 20,000 hours they got engine swapped with a re manned crate direct from Ford. Many times after the 3rd engine was done, I'd go load them up, 3 at a time on a trailer using a rollback. They'd then go to the East Coast, North Carolina, IIRC, and they'd get what they called, ReBoxed. They'd take the Ambo box off the chassis and put it on a brand new chassis. After the 3rd Re Box, then the box was retired and not used again.