Im looking to get another Cummins in the next week or so and had some questions about the 6 speed. Ive had my 2000 since '04 and the NV4500 seems bullet proof (knock on wood). Ive found one 2007 with the 6.7 which i believe has the G56. Another one is an '05 with the nv5600. Which one would be best? Is one prone to failures? The truck will not get bombed too much. Just the basics and if i get the 6.7 all the EGR stuff is coming off since it wont ever have to pass emissions. By basics i mean intakes, full exhaust, and probably an edge module. Just looking for everyones 2 cents.

 

the g56 in high horsepower application will desinagrate 4th gear. from what i have read. i have the nv5600 in my 05 and i love it the only thing really different is the reverse location. either one is tough in my opinion

 

Without a lot of upgrades the G56 should be just fine. Now if you start getting crazy with the truck, the NV5600 will be better.

 

G-56 hands down!

 

G56 is aluminum
NV5600 is Cast Iron.

A cast iron case will not flex.

 

The G56 is fine for mild to medium power increases, with a better clutch of course.

The NV is preferred if you're going to be sticking your right foot into the floor boards alot with medium to high power increases, or for truck pull events, etc..





-Kris

 

Just depends on what you will do to the truck and what will be done to it

 

what HE said...the g56 has an aluminum case. the benefit is weight reduction, while the deficit it a compromise of strength. the torque load will have a more noticable impact on aluminum than it will on iron. the getrag was a fine trans for a 'vette, but the cummins can make short work of it due to the weight being moved, and the torque involved. they're both good though. my preference is the 5600.

 

If I ever go to 6 speed in my Ford, Ill be looking for a G56, simply because it wont ever hook up to anything, so it should be fine, and I like the smooth shifting tranny. Im sure my rear end would go before the G56 would

 

Smooth shifting goes to the NV5600 IMO. I can't stand the G56. It's bloody notchy and blocky. It's just as bad as the ZF6 i have now.

Once the NV5600 is broken in, they shift like butter!!!!