I was looking at ways to gear the truck lower and not suffer mileage or speed related issues. Started thinking about adding a planetary reduction. I was thinking of trying to find a 1.2:1 reduction so I could effectively turn my 5 speed into a 10 speed based off of the new Eaton transmissions. It would basically have the same effect as running a 4.26:1 rear end but would have the benefit of being selectable. What do y'all think about using a planetary reduction to turn a M5R2 into a M10R2?

 

Gear vendors has an Overdrive/underdrive setup that should be able to achieve what you are looking for.

 

Thanks.