I just picked up an 07 2500HD "classic" (old body style) 6.0 5-speed manual, 4.10s.

I purchased it to tow, but only tow around 6000 lbs (so loosing a little towing capacity will be ok w me).
I need it to be my daily driver, and it will see a fair amount of interstate travel. I'd like better gas mileage. I am also thinking some 3.55s or so will make it drive smoother.

My questions are:
Will there be a down side to switching to say 3.55s?

I have the 5 speed manual, so I have a pretty much unusable granny 1st gear now.
My father in law has a Dodge 2500 with a Hemi and 5 speed manual (same NV4500 I believe). It has no issue with its 3.54s (or similar). The 6.0 should be equally able to pull itself along, right?

What would be an optimum gear ratio ( I may go w slightly taller tires - nothing over 33" ).

What gear choices do I have while keeping the 4.10's carrier? I'd like to avoid the expense of a new carrier also... Are 3.73s as low as I can go (numerically)?

 

3.73s is it as far as a higher gear ratio is concerned. I wouldnt go and taller than 3.73 anyway with 33s. Im running 35s on a tuned dmax and it needs some more gear so Im sure the 6.0 would be worse.

If you can wait I might be interested in swapping front gear sets with you. We cant swap rear gears unfortuately since I have the 11.5 rear and you have the 10.5.

Ill be doing my gear swap end of this year.

 

Yeah, too bad we couldn't just swap gears. Unfortunately I have a 2wd, so the front swap will not work either.

I plan on running 33s, as the 35s rub the front bumper. It sets plenty high for a 2wd, so I don't want to lift it. In fact I was considering cranking down the t-bars and removing the rear blocks to lower it 2" or so.

Why do you think you need more gear? I'm not concerned with the truck being quick, it is too big and heavy for that. Besides, that is why I have my 02 Z28, and LS1 Vette.

My priority is interstate, especially when pulling (you are not supposed to use 5th then, right). I think the super low 1st in the manual trans will make numerically lower gears usable.

 

Anyone?

Mods, should this go to 8-lug?

 

i would do it, remove the rear lift block and decrank the t-bars to match, make sure to get it aligned afterwards, but it would rub with a 33 so i would get a ~31 inch tire.

 

I think swithing out the 4:10's for something smaller would be the worst mistake you ever made. It will get worse gas mileage with 3:73's than with the 4:10's. Your truck is big and heavy so the 4:10's are just what you need to get that thing rolling.

 

You could use a gear vendors or US gear 20% or 30% OD units to give you more gear for hwy, and less for when you need it like towing.

Gear Vendors work better becouse you can switch on the fly, and US is a little more reliable since you don't have that feature. Either way US is much cheaper so I would go with this one, and rev a bit more.

 

I considered the Gear Vendors unit. But it is a little pricey.

I didn't know about the US Gear product. According to the site they have it for TH350s and TH400s. No listing for the NV4500...

As far as the truck being sluggish with 3.55s, I don't think you guys understand how low the 1st and 2nd gear in the NV4500 is. My father-in-law has a 2500 Dodge extended cab long box, and it moves fine with the Hemi/NV4500/3.5Xs... are you saying the 6.0 isn't up to the challenge?

 

strictly by the numbers, a 3.55 rear would be fine considering your gear set
1st - 5.61
2nd - 3.04
3rd - 1.67
4th - 1.00
5th - 0.73
Rev - 5.04

on the 1500s, they had 3.42s & 3.73s with the NV3500, and they share the same 4th & 5th ratios

 

Just to clarify, are you saying 3.73s are as low as I can go (numerically) on my current (4.10) carrier?

Thanks Zebra. I realize why others are hesitant to say 3.55s would be ok, but the NV4500 should make it fine. If a Dodge can do it so can we, right?