The Chevrolet factory installed Tandon Axle made from 1956 thru 59 used a Power Divider Auxiliary transmission made by Truckstell and their own Corporate 15000# rears. The Power Divider allowed the operator to select from front axle only or both axles. It is a three speed unit with Low-Low (2.22:1), Low (1.22:1) and Direct Drive (1:1). If you put that behind a 5-speed transmission you end up with a 15 speed truck!
Truck could still be retrofitted by outside jobbers so anything is possible!
1957 was the first year Chevrolet offered "Full Air Brakes" as an option.
I don't have any knowledge or literature on trucks made after 1959, but they might have the same set-up available...
Mike B
