I had a brand new 72' 3/4 ton / one ton with a 304, 4 speed. I say 3/4-1 ton because that truck was pretty much a pre-curser to what is offered these days.
The truck had single rear wheels (split rims mind you) with the extra leaf style of helper springs. You would run out of tire sidewall long before springs.
Even with 4:10's, the truck got an honest 14mpg but man what a buckboard. So, I swapped it in on a 73' Scout with the 345. Chicks just did not dig the ride, lol! That year had some kind of GM emission system adapted to it. Got 8mpg on a good day then the first gas crisis came onto the scene. Good thing my buddy had a station. Used to fill up at night after hours.
Around 82 or 83, I picked up a 75' 4x4 pickup with a 345, 4 speed. It was sitting out in a field so I had a bit of work to do to get it up and running. The exhaust was shot with even the manifolds cracked. I found headers available so I put some on and had the rest fabbed up at a local shop. I ran two glass packs with down pipes just aft of the cab. I put a Holley 650 dual pumper on. The front brake calipers were shot and I ended up sending them to Raylock for rebuilding. NAPA had the back brake cylinders in stock. Other than that, I was good to go. Put quite a few miles on that one at another 8mpg or so, lol!
My last binder was about a 70 give or take dump truck. Old municipal job with a 345, 4speed, ten foot plow and manual steering. I bought it for working around one of my farms. Never did put it on the road. On more than one occasion, the engine died and I would end up pulling it out of the woods or a ravine with my tractor. Finally rebuilt the carb to stop that.
During the two years that I had that beast, we had little or no snow so I sold it to a local school district for their lot use. Some guy blew it up by overrevving it.