Join Date: Apr 2008
Location: A little house on the prarie, NE
Why do you need it? The 5 speed allisons have about the ideal rpm range for mileage and pulling power once you do like most and go larger with tires. The 6 speed runs too low of rpm's once you put bigger than stock tires on it. Lowering the rpms just lugs the motor. It will run higher boost, which uses more fuel.
Jesse 2004 LB7
Lots of miles
Built by Husker Diesel
1995 Chevy 2500 - 12v/NV4500 Swap