Differential identification

[Paul Singleton]

I know that the smaller axle used in the one ton trucks will fit from 1971 back to about 1948 and back further if the side gears are swapped to match the splines on the axles. The bigger trucks are probably the same as far as being interchangeable with many years. The 6:17 ratio was still in use into the 1970s, but I have never seen a numerically lower ratio in a truck. Years ago I helped a friend change the engine in a forklift, it had a 235 and we put in a 350 V8 because we had one. It also used a GM axle with dual wheels with 8:25/20 tires, but I don’t know what the ratio would have been.