I am still looking for a newer reference that I have but according to my 1939 catalog the FC, FM and FW hubs all use the same indicator spindle. The only thing that you must watch for is the axle length. The spindles for the 5 3/4 inch axles are different from those for the 6 1/4 inch axles. The part numbers for the AW hubs are different suggesting that there is some physical difference from the "F" series spindles and thus a lack of interchangeability.
Paul Patzkowsky Longmont, Colorado