I was wondering if the durango used a 3.92 gear ratio in a 9.25 inch rear. I need one for my ram 1500 but all the 3.92 ratios rears i have found in junk yards are 8.50 inch rears.

 

What year is the durango and the year of the ram truck.

 

My SLT+ has a 3.92 gear ratio in a 9.25 inch rear.

While there was no rhyme nor reason for which got 3.92 verses 3.55 and/or 9.25 verses 8.50, they did come both ways.

Generally the pair you are looking for was in the Durangos that came with the factory towing options. Look for a hitch as you cruise the junk yards.

HTH,

IndyDurango

 

How sure are you that your Ram 1500 came with a 8.5 rear? Is it a bare bones 2WD?

Every Ram 1500 I've seen from 1994-2008 have had a 9.25 rear end.

 

Brad:

To add to what Indy has said, I think you will find that the Gen 1 Part time 4x4 Durangos had the 9.25 inch rearend along with the 4x2 models.

The AWD models had the smaller 8.25 inch unit. This also goes for the Gen 2 models.

Again, the Gen 2 4x2 models also had the 9.25 I think.

As far as the ratio goes, the 3.92 gearset seems to have been put into 33% of the D's while the standard 3.55 was at 66%.

This will explain why the 3.92 is a bit harder to come across.

Don

 

My 3.92 gear ratio in a 9.25 inch rear is AWD... or back in 2000 they called it "full time 4x4."

As I mentioned, there is no real rhyme or reason, just tendencies.

 

Indy:

Thanks for the reminder that the R/T package which was AWD as standard came with the 9.25 gear.

I do recall seeing several non R/T Gen 1's with the AWD T case that had the 8.25 rear gear.

The supposition that more than one D owner has come to is that they had the smaller rear gear in D's with the AWD since the rear end would never see 100% of the engine power due to the transfer case being fixed at 58 rear and 42 front.

This would also explain why the 4/2 Durangos got the bigger 9.25 unit.

All of the AWD Gen 2 D's had the 8.25 gear as far as I have seen.

Don

 

I've been doing a lot of research on swapping my 8.25" 3.55 rear end and front end with 3.92 gear ratio for towing with my 2005 Durango. I've located a limited slip differential 9.25" for $700 and a front carrier assembly for $400 in a salvage yard. They are harder to find but available. My plan is to have the rear axle assembly swapped and front carrier assembly swapped and then sell the old 3.55 parts on Ebay. Looks like everything will swap in without major modifications. Labor at a local 4x4 shop is $900. I looked at the possibility of doing it myself but I think for $900 I'm better off having the shop do it. The dealer will flash the computer to reflect the change for a little over $100. The alternative was to keep the 8.25" rear end and just have the ring and pinion swapped and new master bearing/seal kits installed. The 9.25" rear end is stronger with bigger bearings and axle shafts. The brakes are the same so looks like 9.25" for a little less money than swapping the ring and pinion is the way to go. I'll let you know how it works out.

With the 3.55 gears and 5.7L Hemi I'm rated at 7400 lbs towing. It goes to either 8900 or 8950 by going to 3.92 gears. If I could find a 4.11 set of gears I might be temped. However, with the front 8" reverse cut gears I would have to go to a 3rd party to get the 8" ring and pinion. I think I'd go with 3.92. If that's not enough I'll go to a Dodge 2500 with a Cummins Diesel and never have to worrry about it again,

 

Okay. I picked up a used 9.25" 3.92 rear differential assembly from a local salvage yard as well as a front carrier assembly (3.92) for $1000. A local 4 x 4 shop is going to install them for me for $830. I plan to sell my 3.55 rear axle assy and front carrier assembly when I'm satisfied that everything is working. They only had a traction control version of the rear so I guess I'll have traction control when I get done. It will be installed next week. The dealer has agreed to flash the computer for $48 to reflect the gear ratio change. The estimate for just changing the ring and pinion was $2200 parts and labor. I'd still have an 8.25" rear end. We'll find out if there are any surprises but look like it will cost me $1830 to make the swap winding up with a 9.25" vs 8.25" rear end, traction control, and 3.92 gears. I'm happy with that. I expect I'll probably be able to get $800 to $900 for my old parts (only 55K miles). I'll let you know how it works out.

 

Ledoyle:
Good luck with that project, and please do let us know how it works out.

Don