Not sure when they started but they are 1 ton drrw only up thru 1972.
I have a "49 with them & my boss (dealer principal) has a 72 C30 with them.
1973 they stated using 16.5 wheels.


BC
1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc
1949 GMC 250 project in waiting
1960 C60 pasture art
Retired GM dealer tech. 1980 - 2022