Look around for tandem axle gas powered trucks. International, Ford, GMC I know all used a Spicer 6031A among other models. Look for the "A" letter. That will give you a 24% under, a direct and 17% over. This was commonly used with a 5th direct 5 speed or a 4 speed like a sm420 or SM465. That A ratio set splits the main box gears nicely. You'll have about a300 RPM drop between gears. Under the grease on the driver's side of the brownie is an ID plate that has the numbers on it.
