My parts books show Chevrolet only used one Spicer 5-speed from 1956-66. They all used the same Drum (Spicer 20B-54). You'll need to contact Dana/Spicer to see what other transmissions might have shared this drum. Drums from other manufactures won't have the same bolt pattern or drum center disc offset. You'll need to match your output shaft Flange bolt pattern with the Drum.
Call R L Jackson in Port Deposit, Maryland and see if they can help, they sell used truck parts...Phone: (410) 378-2481
Mike B
