I have a 12 bolt with 3.73 gears from a 65 1/2 ton in my 1954 1/2ton. The 3.73 gears are a pretty good compromise between low end and high end performance. I also have a 1955-1962 Chevy 1/2 ton three speed overdrive trans that allows me to really drop the rpm's on the highway. Cannot drive under 50 mph in 3rd gear and overdrive or it lugs down, 55 mph and above is best in 3rd and o/d with 3.73. I did have the 55-62 rear end with the 3.90 gears and overdrive trans in the truck for many years and think that was the best combination for take off torque and highway speeds. The GM engineers knew what they were doing when they designed the 3.90 rear end with the three speed overdrive trans. It takes a little more diligence to find the trans and hook up the electrical on the 3 speed overdrive but is well worth it to have the ability to kick in and out of overdrive with the gas pedal in 2nd and 3rd gear - the 2nd gear take offs when driving around town and the free wheeling at low speeds. Complete operating/driving instructions are in the 1955 and later Chevy shop manuals(available on line). After market (Hurst?) shifter would be needed without existing column shifter and shifter clearance from seat frame might be an issue to resolve.
Last edited by truckcamper43; 10/20/2011 3:47 PM.
