Willy,
I should tell you the M Series was broken down into 4 different chassis options as follows:
MA = 1-1/2 ton, 131" wb, Single Wheels
MB = 1-1/2 ton, 131" wb, Dual Wheels
MC = 1-1/2 ton, 157" wb, Single Wheels
MD = 1-1/2 ton, 157" wb, Dual Wheels
So,you would ID your truck as a 1931 Series MB.
Chevrolet didn't have any "factory" accessories back then, they were all dealer or owner installed.
Don't quote me but I think the first year Chevrolet offered a strap-on directional unit was 1946 for the trucks and 1950 for the cars. Prior to that they were all aftermarket...
The stick on the column could be for turn signals or trailer brakes.
Mike B
