Starter wires poor connections; they vibrate loose on the 6.9.
Body mounts rot, vacuum problems with shifting in the C-6.
Also, all old Fords have switch problems in the steering column turn signals, and the brake lights don't ever work right.
Wire connectors are made of crappy alloys, leading them to corrode.
Power steering boxes are bullet proof, but are neighbor haters because they leak out of the bottom seal.
I am in the salvage business, and haul a lot of metal around all day long. Sometimes I travel 100 miles a day.
Anyway, I need a tough truck, and old Fords are just that, preferably Canadian models (assembled in Canada). Put it this way, Chevy or Dodge doesn't have a chance mechanically or chassis wise.
What I am trying to tell everyone, is from 1980-1989, Ford made the toughest trucks ever made, if you don't care about turn signals or brake lights never working of course LOL.
I have been hauling metal for 8 years now, and had 2 Fords. The first one was a 1983 5.0 F. It never let me down. The first thing I did to it when I bought it was a timing chain and steel gear. It didn't need one, but I knew I would never have a problem with it. 5.0s are bullet proof, known to even run without oil!
The truck never did die. I wanted a 1985 diesel F250, the F150 was towed because it looked like it went thru world war 1-2 and even Nam LOL, and it did in truck world of scraping metal! The salvage business is one of the hardest businesses on a truck. Now I have a 6.9 250 and do the same, but don't burn any gas and have great power on the highway.
Weight was never an issue for both trucks, whatever you can fit the old Fords will handle, not legally. If you try this with any other trucks, you will experience failure; frames bend, snapped leafs, axles break and blown rears. Also Chevy's overheat with a load. Both the half and 3/4 ton Fords I had 4 tons in, no problem! It's not safe, but it is incredible!
If I could post pics, I would show the scrapyards where you will see nothing but Fords. 95 percent Ford, 5 percent Chevy and Dodge. Dodge is a great truck, but Ford used a thicker frame rail and treated the leafspring steel perfect; they don't snap or bend like Chevy's do. Also you see more more Fords in auto junkyards because Ford produced so many more trucks than Chevy and Dodge put together!