Jim,
Casting number 837231 is a 1933 Block part number 364314.
Casting number 836961 is a 1933 Head part number 836960.
These were used on Models CA, CB & O.
There were four 1-1/2 ton "O" models available;
OA = 131" Single Wheel
OB = 131" Dual Wheel
OC = 157" Single Wheel
OD = 157" Dual Wheel
Mike B
