After doing some math, I found that the stock axle ratio from the automatic transmission equipped XJ's would work pretty well. The 3.55 gear ratio would put my engine back into it's intended RPM range, and then some. Axles with the 3.55 gear ratio are plentiful in the junkyards so it was just a matter of searching. I had originally intended to find a Dana 44 to put in the rear but the asking prices, both at the junkyard and through private parties, were more than I wanted to spend.
From what I had read, the Chrysler 8.25 29 spline axle found in late model XJ's was very strong and recognized as being able to accommodate 35" tires with a locker. Since that is bigger than I ever intend to go, the Chrysler 8.25 fit the bill and was available at a much lower cost. Soon after making this decision I ran across a 2001 8.25 with 3.55 gears and only 89,000 miles on it. Perfect! I picked up the axle at a junkyard near my house and it was in beautiful condition. It didn't need any work except for a brake line which had been cut during removal. This wasn't an issue since I planned on putting a longer brake line from a mid nineties Dodge Dakota on it anyway.
I was also lucky enough to find a '96 Dana 30 in 3.55 at the same junkyard. This one had about 150,000 miles on it. Although it needed some work, the price was right and would provide the late model axle shafts capable of accommodating the larger 5-760x u-joints that I wanted to use. It also had a lot shallower film of rust than my current axle! Let the games begin!
This is the Dana 30 and Dana 35 that came out. Note the leakage and overall scabby appearance...under the mud!
This is a picture of the 1996 Dana 30 prior to the restoration and rebuild phase.
Here is the 2001 Chrysler 8.25 29 spline...not much restoration to do here!
Here is the new Dana 30 with a few hundred miles on it after the restoration and rebuild. I completely stripped and wire brushed the axle housing, axle shafts, and any other components that would stand up to it. I then painted the axle housing with primer and Rust-Oleum flat black. I decided to use red on the differential cover. I think it looks good with the Warn diff. guard, otherwise the red is too much. I replaced the ball joints on the passenger side, installed higher strength 5-760x u-joints in both axle shafts, and installed Superior axle tube seals to keep the Northwest's mud and water out. It also received a complete brake system replacement with new disks, calipers, and pads. Yes, that is power steering fluid all over everything and yes, it is now fixed:)
The Chrysler 8.25 came out well too. I just painted this axle since it didn't have any rust on it to begin with. It didn't need any work aside from the brake line. I used a mid 90's Dodge Dakota brake line which netted a lot more length than the stock brake line. I also used the springs off of the 2001, which were in much better condition than my old rusty ones, with my Skyjacker add-a-leaf. I had new high strength u-bolts made, purchased a shorter stock driveline from George the Jeep to fit the AX-15/Chryco 8.25 set-up, swapped in my driveline u-joints, and was ready to go! I also left the rear sway bar off to allow for better articulation on the trail. The red differential cover is a bit much but I plan to put a black diff guard on it at some point in the future. This should mute the red nicely so it's not so obnoxious!
The end result is fantastic! On the street the XJ accelerates briskly in town and cruises on the freeway without a need for downshifting, except for mountain pass-type hills. It crawls much slower on the trail and the stronger axles give me peace of mind knowing that they are overbuilt for my 31" tires and open differentials. It also drives as smooth as glass. I feel like I got a new Jeep after the swap!
