Dieselrick, how do you figure that the NV5600 is geared for a higher rpm? They both have a 5.6:1 first gear ratio and .73:1 overdrive ratio. The extra gear is going to help the 12 valve by reducing the RPM drop between shifts. I do agree that unless you are towing alot or getting a really good deal a 5sp would be the way to go. IIRC the NV5600 6th gear is problematic and parts for that trans are hard to find and expensive.

Let us know what you end up doing dpgcummins12v

So i was wrong It wasn't a nv5600 it's the g56 and I ended up getting it for 2200 with everything (ecu wiring clutches driveshafts tcase xmember and tranny) I still need to find the adapters tho I went to southbound and they have the flywheel and clutches I need but not the bellhousing or starter adapters. Any other leads on where I could possibly find thos adapters?

Look up my thread "1997 Dodge Cummins G56 Conversion"