Axle differences

[Joseph Burgess]

Ok went and picked up my donor axle and diff at the salvage yard, my truck has the 9.75, 3.55 limited slip S939J the one i was given is identical except it is labeled a S939A what is the difference if any before i do the swap this weekend. I know from the ford site that the S939J is 99-00 expedition, and the S939A is 98-99 expedition, navigator, but other than that it doesnt say much, could it be one is air ride and other is not and will that make a difference aswell as mine is not air ride. Any info would be greatly appreciated thank you

 

[ExplorerTom]

Lug stud sizes were changed around that split. 12 mm to 14 mm (I think).

 

[Joseph Burgess]

Yea mine has the 12mm studs , im hoping its just a yearly code change as it all looks the same will find out this weekend

 

[RMARTIN]

Ok went and picked up my donor axle and diff at the salvage yard, my truck has the 9.75, 3.55 limited slip S939J the one i was given is identical except it is labeled a S939A what is the difference if any before i do the swap this weekend. I know from the ford site that the S939J is 99-00 expedition, and the S939A is 98-99 expedition, navigator, but other than that it doesnt say much, could it be one is air ride and other is not and will that make a difference aswell as mine is not air ride. Any info would be greatly appreciated thank you

I have a 2000 E.B.,
Awd with 177,000 miles and mine has started getting noisy also. My mechanic said the racers were pitted when he checked the fluid level. (I read your other post titled the same as this one). Not sure about my lug stud size. I have the 9.75, 3L55, S 939 J.
H9 Axle code on door sticker.
Born on date 10/99.
It has air suspension.
Pictures included if I remember how to do it.

Sent from my Pixel 3a XL using Tapatalk

 

[Joseph Burgess]

Your axle is same as mine, should have 12mm studs and yiur lug nuts should be 3/4, i got home today from work and pulled my rearend and swapped with the donor after changing the diff oil, once buttoned back up took for an spin and no more sound, now mind yiu the donor had more miles on it so im gonna have my original rearend rebuilt new again and put up for hard times lol.

 

[Joseph Burgess]

Oh and if you are looking for a donor vehicle a 98 -99 expedition with axle tag code S939A is identical to the S939J same ratio and both have the posi traction .

 

[Joseph Burgess]

One question, your mechanic said your races were pitted qhen he checked the diff fluid level, unless he pulled the front pinion bearing seal and then bearing itself he couldnt see the races and same goes for the axle bearings , goes for all the races just pulling the rear cover alone wont give visual access to the races either, fact is if its starting to make noises its time for a rebuild