If we race or pull with our bombed Dodges, we pay the price through the drive train, specifically the manual transmission and clutch.
I've read so many horror stories about blowing 5th or 6th gear, main shafts, yada, yada, because of the extra ordinary torque applied to inadequate-for-the-job parts.
A real enemy with manuals is shock loading. You can't avoid it. Another is, any gear higher than 1:1 is out at the end of the mainshaft foodchain, and physically a very small gear, relatively, at that. Many of those overdrive gears are addendum at the rear of the trannie box without a lot of support.
Maybe we should take a new tack on an old problem. Why not numerically lower the diff gears and not use any gear higher than 1:1 at all? The 5th gear in an NV5600 is pretty good sized compared to 6th (O.D.) and better supported. The 4th gear in an NV4500 is likewise a pretty stout gear with way better support. What about running 3.07:1 in the pigs, or 3.31's or even 3.54's?
With 3.07's, and taller tires, maybe you could peak out a couple gears from the top. Sturdier yet.
Maybe you've all thought of this before and it goes without saying, but I don't see anyone doing it.
You see very few of the 60's-80's medium truck transmissions with higher high gears than 1:1 in 5th or 6th. I think there is a reason.

Years ago my '82 Jeep CJ8 came with a T-4 (4,03/2.37/1.50/1.00/3.76R) and 2.73:1 axles. WHAT? 2.73:1 The T-4 was a joke, as 3rd gear was the size of an oreo cookie and blew the first time I used 4WD. I needed a replacement and for sure it was not going to be another weenie trannie. I also wanted taller tires. I settled on a Ford T-19C, mid ratio, 4 speed, all synchro, truck transmission (5.11/3.03/1.79/1.00/5.63R). It came out of a '79 Ford 1 ton.
Notice with taller tires the 5.11 low gear got closer to the 4.03 low on the T-4. But the big deal was the T-19's 1:1 with taller tires was now a defacto overdrive. Alright, this was not the ultimate off-road trans, but it was great on the highway, and sturdy too. My Jeep ultimately burned through 3.54's, 4.10's, and finally 4.88's with bigger/stronger everything. It now has a NP-435E (6.69/3.34/1.74/1.00/8.26R) and even with 37" tires won't be doing freeway speeds.
So, if you're still here, let's hear what your gearing solution has been for pulling/racing and not using O.D. at all.
regards, as always, jefe

 

They don't make taller gears for our axles. 3.54 is the tallest ratio available for both front and rear axles. A 2wd truck would have a better option.

Taller rear diff gears are physically stronger as well. And they eliminate the need for OD tranny ratios (which are weaker, as you mention).

That's why racers go with shorter tranny gearing and taller diff gearing.

Look at how a Lenco is set up-- that's a very strong setup.



I'd recommend a Lenco for a brute strength application-- or a B&J, Liberty, Jerico, etc... Lenco is probably strongest.

JMO

 

You are right. I can't find a 3.31 in a Dana 60. I did find a Dana 80, 3.31 at Drivetrain.com
I'll keep looking.
regards, as always, jefe

 

Only thing I can think of is the early 1st gen autos with the 3.07 gears.. but I think it was a Dana 70.. and guessing it was a 60 in the front with the pumpkin on the right side..

 

Yep, and I think the front was a 61 or some variant of the 60 that is odd ball. I believe you are limited on D60 gears to 3:54. I went through the great gear hunt looking for a higher ratio combination for my corp14 and D60....ended up doing a tranny swap as 3:73 was the only common ratio and it was not enough over 4:10 to warrant.