I think there is some confusion going on. The parts manual lists the side gears as having 10 teeth, 1937-42 all COMM, and 1946-49 all 1/2 TON COMM. #370225. There is no mention of spline count for the smaller axles. Splines and teeth are two different things.

http://chevy.oldcarmanualproject.com/1929_57chevyparts/index.htm