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The ratio should be on the tag on the cover.


Here's an example code: 4L10x88xxxx


4_10 = gear ratio

L = Limited Slip (any other letter means open diff)

88 = Size 8.8 ring gear

x = Not important plant/date info etc


You will also want a 96+ axle from an Explorer, not a Ranger! Other than a handful of special packages, Ranger 8.8s are only 28 spline. All Explorers are 31 spline, but the 96+ have the disc brakes for an easy upgrade!

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95+ have disk brakes. bring a good flashlight and something to clean the crud off the tags. :thumbsup: Oh, and posi units will typically have a second tag on the diff cover.


While you're at the yard, you'll need the proper flange adapter. I think it's the crown vics and areostars (ones equipped with their own versions of the 8.8 at least) that have them. Get the 4 bolts too. they are metric and super strong. failing that, the dealership is the place to get them. don't even bother with a hardware store. chances are real slim they'd have metric bolts strong enough.

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When I look for axle assemblys half the time the tag is missing. Seems that's the second thing gets removed on a vehicle. Owners manual is first. Suggest any one going axle shopping learn how to remove cover and count teeth or how to turn axle while counting turns of pinion. And the difference between open and posi.

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Good point. :thumbsup: on that note, while I highly recommend popping off the cover for the axle you plan to purchase (so you can look for metal shavings, missing teeth, or like the one I found that apparently was in a side impact and the axleshaft was pushed into the carrier and cracked the center pin) that can quickly become a overwhelming and super-messy chore if there are 20 explorers in the yard. so here's what I do in the event the tags are missing.


When you spin one axle shaft and the other side rotates together at the same speed in the same direction, it's a good chance it's a posi unit.


When you spin one axle shaft and the other side rotates the opposite direction or if the other side is stationary and the driveshaft turns, it's a good chance it's an open unit.


to determine gear ratio (assuming that the driveshaft turns freely or is missing):

If the unit is posi, rotate one axleshaft around one complete revolution and count the number of times the driveshaft or driveshaft flange rotates. just over 4 times is 4.10, 3 and a half times is 3.55, etc.


If the unit is open, keep the other axleshaft from spinning (a helper, or maybe a box wrench hung on one of the wheel studs) and rotate your side around twice and count the rotations of the driveshaft.



oh, and for the 8.8 specifically, do your darndest to grab the calipers. the core charge at the parts store is insane. :ack:

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you can also look on the sticker on the drivers door for the axle code. pretty sure the codes for 4.10 are 42=4.10 open and 4d=4.10 lsd. i have posted the code chart on here before i believe

edit: i found it

43 Open 3.08

41 Open 3.27

42 Open 4.10

46 Open 3.73

45 Open 3.55

D4 Limited Slip 3.73

D2 Limited Slip 4.10

L73 Limited Slip 3.73

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There is also gear ration or the teeth count stamped on the ring gear. You may have to turn it a tad but it'll be there.


Most of those tags on the covers are not there because out here they pull the diff covers to drain the fluid before they set them in the yard.

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