Chevy 80 series were very popular with grain haulers in the 60's that hauled grain from the Texas panhandle and Oklahoma to Houston and Corpus Christi. The earlier ones came with 348 and later with a 409. Most 348's were replaced with 409's. I think 1965 was the last year of the 409. It was replaced with the 366. Most grain haulers held on to their older trucks and put a crate 409 in when the old one blew. These trucks were single axle from the factory and a drag axle added. They usually pulled flatbeds with wooden side boards. Twin screws were offered but they were for vocational trucks such as mixers. A twin screw requires more power, so they were not used on longer hauls. There were literally hundreds of them that would make 3 loads a week from the Texas panhandle to the port. Many of the Chevys were wrecked from driver fatigue and drivers bouncing pills off the windshield. Almost all of the rest were run until there wasn't much left and therefor not many survived. The Chevrolets finally gave way to grain haulers buying used Diesels. The oil embargo was pretty much the end of long hauling grain with trucks. They couldn't compete with rail. The roads here in the Texas hill country have been widened, but the grades have not changed in 60 years. Hills that would pull a 409 down to 5 mph now pull my trucks down from 68 on the cruise down to 50 mpg.