5 or 6 Speed?
 

I am looking at buying another Cummins (Addicted :rocking:) I'm looking for another 2nd gen 24v and I want a manual with a short box to use as my fun truck. I've decided on all specifics I want except for the tranny. Should I prefer one over the other? I hear the 5 speed is easier to get replacement parts for... I'll mainly be using it for off road adventures, and (hopefully) will be building it up to compete in Baja style races. Any input is appreciated. Thanks!

it's really up to you.

So there's no major pitfalls with either transmission?

Third gear in the nv4500 is a weak gear. And 5th gear nut backs off but thats fixable. Still an awesome tranny though. If its a stock nv4500 it has a smaller input shaft. I have a couple buddys woth nv4500s and they love them. They are both just over 600 hp with dyno sheets to boot on vp trucks and they have broke gears a few times. The nv5600 has a larger stock input shaft and does not have a weak 3rd gear. The parts are a lot harder to find like you said. To each his own. If you are going sled pull with it I habe heard that a lot of the guys like using the nv4500 because its legit about 140lbs ligher than the nv5600.

What for speed and mpg differences are there between 5 speed and 6 speed?

The 5's and 6's are the same final gear ratio(well very close) On the 6 there is just an extra gear between 3rd and 4th compared to the 5 speed.

So not really much difference in mpgs?

No if anything you should be worried about having 4.10's. that's what I have with my 6 speed and I hate them.

For a fun truck that's not going to be towing heavy, the 5spd would be more user-friendly. The 6-spd's advantage is that it has that one additional ratio between 3 and 4. If the truck will have a leisurely life, that gap's not a big tragedy.

i have 4.10s with an nv5600 and i love it. i just dont drive over 70 on the expressway most of the time. i dont go on the expressway much any how. i do a lot of town driving the most. and in the summer time i average round 19mpg if i dont drive like a dummy. but thats with coasting to lights and all that happy stuff. not too bad if you ask me. in the winter time im lucky to see 16 though. winter fuel kills my mileage up her in the north east