4dodge5.9c

Hello All
I have been looking for information on Aux transmissions. I am hoping that someone on this forum can help or point me in the right direction. I have been looking at both US Gear and GV to do this with. I know that the US Gear is no longer in production, and has a better GVW @ 35k and the GV @ 18k. Does anyone have experience with either of them? Like one better than the other? Any input would be helpful. Also what are their any alternatives other than going to larger tires? The rear diff has 3.55 or 54 in it and it is a 4x4 dodge truck with a 5.9L 24 valve Cummins. Thanks for any and all help.

SIXSLUG

What are you trying to do? Increase mpg? Increase towing capacity?

bentwings

I have a friend that has a GV in a 12 valve with a NV4500 5 sped. He has 4.10 gears as I do. He says he gets 24-25 mpg if he keeps the speed around 60 without the trailer. His trailer is not as heavy as mine so he gets about 1 mpg better towing mpg. He says that it's hard to keep it in od pulling the trailer except where it is dead flat and no head wind. It appears that the motor lugs in od so you have to give it more pedal. We both have 3500 quad cab duallies.

If you have a 3.54 gear your final drive is really too high (numerically low). You will have to go very fast to keep the motor speed up which puts you at a severe aerodynamic disadvantage.

Check the GV site for the ratio chart.

The GV does allow split shifting which is nice in the mountains or very hilly country. The NV4500 does not have the best ratio split.

If you can get a used one at a good price I'd get it and plan on changing rear ends or gears.

totalloser

Dropping rear end gear ratio to accommodate an overdrive system seems wrong headed to me. Any OD system will add geartrain inefficiency losses. Taller axle gears will not.

The only place I would use an auxiliary OD would be with a transmission that has no OD to begin with. For less jump between gears, the 5600 or G56 might be a more practical solution. Even with 3.55's the gears are pretty close together. Almost excessively so, but for towing it's very nice.

SIXSLUG

I'm looking at the 35K part....he needs a bigger truck. If for anything for safety. I would think a 2 ton or a 5 ton would be more practical, especially for the braking and heavier driveline....