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A Couple Pre-Junkyard D30 Questions...


NAXJA Forum User
Moodus, CT
Going to the JY this weekend. Looking for a D30 that has 4.10s. My understanding is that they appeared in all 2.5L Jeeps. I would just like to confirm this, as well as find out about any other options that may have come with 4.10s but mainly how to identify them.

Also, if I find a vacuum disconnect axle, can I put a cover plate over the fork thing and swap in regular shafts like the ones from my 97?

As far as my personal experience goes, I've only seen 4.10s in 2.5 5-spd XJs.

They could be in others as well.

You can put a cover plate and swap ur shafts in, you just need a conversion seal, or dremel out for a regular D30 seal.
how do you know the gearing? count the ring and gear teeth?
how do you know the gearing? count the ring and gear teeth?
ring gear teeth divided by pinion gear teath

or you can spin the driveshaft and count the axleshaft rotations
also 4 speed auto 2.8's had 4.10's
also, their should be a tag on the cover, it will tell you what ratio it is
There should be two numbers stamped on the ring gear. The larger of the two numbers (ring gear tooth count) divided by the smaller of the two numbers (pinion gear tooth count) will get you the gear ratio.
So, they had a 2.5L Auto MJ and a 2.8L Auto XJ. Between here and Google I've read that either of these could have them. Can anyone confirm this? Is there a database somewhere of stock Jeep axle ratios? I tried Googling to no avail...
wikipedia says:
Jeep XJs came in several standard gearing ratios:
3.07:1, manual transmission, I6 engine.
3.54:1, automatic transmission, I6 engine with Dana 44 rear differential.
3.54:1, manual transmission, I4 diesel engine with Dana 35 rear differential.
3.55:1, automatic transmission, I6, V6 engines; manual transmission, I4 engine.
3.73:1, automatic transmission, I6, Tow Package, UpCountry Package.
4.10:1, manual transmission, V6 automatic transmission, I4 engine.
4.56:1, automatic transmission, I4, offroad or tow package.
Note: Dana 44 rear ends came with manual transmissions with the towing packages in 1987.