Both the non-syncro 4 speed used from as early as 1931 to 1946 and the SM420 can be converted to an open driveline. The rear bearing retainer on 41-46 has to be changed to a retainer used on 39-46 COE, school bus, or other large truck with an open drive line. Parts book indicates even 1 ton trucks in later years had the bearing retainer for open drive lines.
