My dad bought a new 67 C50 with a 327 4 speed and 15,000 lb. axle for his new log truck in 1967. He had ordered a C60 with 366 and 5 speed and 17,500 rear end but he got worried about how he would pay for the extra cost. A friend of his ended up taking the C60. I think there was a $2,000 difference, the 50 series was about $3700 if I remember right ( I was 9 years old). The truck before it had been a new 63 GMC with 305 V-6, the 327 would pull the GMC in two. He had driven the GMC 4 years without ever doing anything to the motor. The 327 lasted 2 years and he replaced it with a 350. The biggest thing I ever remember about the truck is how often it would break an axle. We'd always have to go to the woods, after dark usually and it was always in a mud hole when it broke. I've spent many cold nights holding a flashlight for him.
The biggest complaint dad ever had was the brakes. He always said it had the worst brakes of any truck he ever had.