Getting the 37s fitted this week
 

I'm Junking my 34.5" (315/70/17) Nitto Dune Grapplers & going for a set of 37/12.50/20

the vehicle is a 2001 RT with
3" Performance Accessories Body Lift
3" Rancho Suspension Lift (stock front driveshaft)
4.56 Ring & Pinnions

I've had this set up for almost 3 months and done over 3000 miles with no problems. It feels fine so much so that I think it will take the 37s so I'm giving it a try.

I'm going to get the Torsion Bars Cranked-up the 8 turns to get me 2 extra inches in the front.
In the rear I'm getting a new set of leaves
Changing the bolt pattern so I can get a wheel with the correct offset but even then going to have to cut back the body at the rear of the front inner arch and possibly notch the frame (or limit turning ) to clear the tyres.

QUESTION
Transfer cases..... are there any with a lower output than my AWD box ?
I'd like to install one if available to compensate for the taller tyre.

Reasoning : I've wheeled a Suzuki Sidekick for years on 35/15.50/15s back in the UK for years so think think my Yank Tank will take 37s as a daily driver

NV231 has a low range of 2.72:1 reduction ratio.
NV242 has a low range of 2.72:1 reduction ratio.
NV233 has a low range of 2.72:1 reduction ratio.
NV244 has a low range of 2.72:1 reduction ratio.


They are all rated the same in LOW operation ratio equally. The HI gear is 1:1 as far as I know with no reduction so it would help you.

I wouldnt if i was you.
A sidekick is a lightweight, powerless lunchbox. The durango is overweight/over powered for its own good. 37"s would eat at the bjs/bearings/steering/ etc.

The only right way is SAS... No doubt about it.