tires made a whole new pickup out of it

The 7.3 was the absolute best diesel our fleet ever had...  it was as simple as a hammer, and although not screaming like the later, more complicated engines, it developed reliable power all the time, even in extreme cold.

Our F450's had 'em with Allison transmissions and twin fuel tanks.  In winter, we'd run ordinary diesel in both fuel tanks, but we'd put about a gallon of regular (non-ethanol) gasoline in the front tank.  Every cold night before shutdown, we'd drive the last three miles home on front tank.  They'd pop right on in the morning, and after a few minutes' warmup, and about a mile of driving, flip to the rear tank and be good for the day.

The only weakness we had, was a few transmission problems... and probably not unreasonable, as we pulled well-loaded 14K trailers often... but I do think the later Allisons had improvements.  We also had one differential that developed some issue, but I can't recall exactly what it was... but I think it may have been a damaged axle seal resulting in low fluid level or something.  I don't recall which axle model it was, either.

New tires, is like new shoes.  Wear the same pair of shoes working on concrete pavement, and after a few weeks, the shoes will wear unevenly, and eventually, your feet, knees, and hips will start to hurt, because your body is all out-of-kilter.  Vehicles have same problem... and of course, some tire designs (stiffer sidewalls, more aggressive treads) yield rough ride, tracking, noise, and squirrly handling.  My experience has been that the solid-axle Class 4/5 trucks with straight axle and independant suspension have had better treadlife than the TTB suspension... but it's simple, and handles well under most circumstances.  On our 450's We generally saw front tire feathering and cupping after about 10,000 miles, so they'd get replaced often, but that would probably have not been the case if we could rotate front to rear.  On our duallys, the front tires were identified as 'steer position', while rears were 'drive position only'... so it precluded doing a front-rear.  We did have one truck where we experimented with steer-position on rear (duals) as well as front, and the general determination was that it wasn't a worthy investment... better to just replace the fronts and be good with it.