Project up date, I successfully transplanted from a donor 1952-54 QD straight cut gears and clutch fork into my 1957 QD18 that had spiral cut rusted away gear teeth and 1/2 rusted away clutch fork. I reused the pinion thrust washer from the QD18 as the earlier QD motors did not use one. Also there was a difference between the pinion gears. The QD18 had a long shank and the early QD had a short shank. This makes the swap ok to swap old QD gears into the 1956-57 QDs, but not the other way around.