Mine 99 5,9 4WD had some trailer tow-package which also included 3,92 rears.

 

Winkie

The easiest and most economical way to upgrade your gears would be to find a donor D so equipped, and transplant the axle assemblies into yours.
Should you go this way, think about also finding a 2003 rear end that will have disk brakes as well.

If you were to go to the expense of paying to have new gears installed into your existing axles, I would go with the 4.10 gears.
The labor is the same either way, and the difference will not be enough to hurt you on the highway. Going to 4.56 gears is a different story.

You can expect to pay $1800-$2200 for parts and labor for a 4x4 gear swap.

I did some research, and found that the 3.92 gears were installed roughly 33% of the time while the 3.55s were 66%.

As an aside, unlike Ford and GM Dodge does not tie the 3.92 gears with their trailer tow package. Both my 01 and my current 04 D have the tow package with the 3.55 gears.

The only way to assure that you got the 3.92 gears was by purchasing the R/T package on the 2000-2003 Durangos OR selecting them as a stand alone option.

Don

 

not sure how you got such a high number... for 4.56 gears its about 160 for the front dana35 and about 270 for the rear if its a 9.25... add a hundred for the master install kit and that only brings you up to less than 700 bucks... you buy the parts and have a shop install them and i doubt that you will end up paying 2000 bucks... forget the 3.92 gears just go straight for the 4.56... it will pep up your truck a bit and wont seem sluggish and honestly really wont hurt your mileage much... will take less force to run your tires and bring your rpms back down...

 

he was including labor for the install in both front and rear axles, the front is difficult in these trucks iirc bc the cover doesnt come right off there is something in the way (cant remember what right now)

 

With tough country lift the 98 has steering drop piece and extra hole in differetial cover for access. Still $1400 for 4:56 from Adams Driveshaft in Las Vegas. Check around 4x4 shops for abetted deal look at James's website. Facebook.

 

I am opting for the 4.10 w/ 33" tires, but just curious who is running 4.56 and what MPG are you getting?

I do more travelling than 4X4 but it would be nice to have the lower gearing when in the dirt.

 

Not much differance from 4.10 to 4.56. Stay with the 3.92 with 33s. My 35s bring me to 3.55 check Adams Driveshaft in Las Vegas. James has gear chart posted. Your talking less than 500 rpm. Not going to help MPG. I gained 2 MPG with 35s.

 

I ran the 3:92's with the 5.9L custom built and ran 15.8 average MPG's on the freeway at 75 mph. Down low power would spin the tires with 750 lbs on the hitch on start out.

Now I custom built my 1998, but just say'in.

 

What ask did you're custom built have? :-D

 

My old 1998 Durango had a 5.9L built motor. I had the engine custom built, trans custom built, and custom built T-case all in one package. I have sense sold it.

Anyway your front axle is a 194 FIA axle, and that is what you need to get the parts for, your rear is either a Chrysler Corporate 8.25, or the Chrysler Corporate 9.25. You can count the bolts on the cover as Sharps stated to figure out which one you have.

In 2000+ there was a change over to the new style front end, the C205F axle, and a few early 2000 builds got the 194 FIA. The main noticeable thing that you will see is that if it has a steering box then it is the 194 FIA, and if it is Rack & Pinion then you have the C205. But again the 1998-1999 and some early built 2000's had the 194 FIA, and 2000-2003 had the C205F.

Just putting that information out there. I use Yukon gears in my builds and Yukon bearings, or Timkin bearings. I only build my own, not other peoples.