[dwcsr]

The dip at the top of the firewall circled is not on a 1950 cab, the arrows show where no ribbing is 47 48 and some 49 looked like this flat and smooth. The circle on the left by the fender was not on 47 or 48 with a floor shift. That little L bracket is a 3 speed column shift only feature. The carb and valve cover are 235 ci engine.

It may be a 49 because there is no ribs on the firewall that I can see. In the back of the cab there are cab mounts. If that attach to the sides if the frame its a 49. if the cab mount is a single mount in the center is a 48. It is not a 47 and it is not a 50. Your choices are 48 or 49.