The speedometers should be the same in size from 40 standard to the 41 -47 pickups. The gauge faces will have different colors from passenger cars vs commercials. There is also 100 mph and a 60 mph speedometer. Drake made the '40 standard metal gauge faces and the later pickup colors were only done in decals to my knowledge.
few 40 speedometer cores that work and other dash parts for a 40 if interested give me a call and i will send you some pictures....... tobby 818-990-0590