28 or 31 axle


ironman

ironman

15+ Year Member

Joined
Nov 8, 2007
Messages
83
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3,101
Age
49
City
louisville kentucky
Vehicle Year
1986
Transmission
Automatic
how can you tell the different i mean what i am counting here trying to figure out. so when i order my moser axles i will know. Any help would be nice dont have an clue when it comes too these axles.:dntknw:

i have the cover off.
 
pull the shaft out of the diff housing and count the splines at the end of it
 
what vehicle is the axle originally from? to sum it up, explorers and fx4 lvl2 trucks have 31 splines, all others have 28. axle tubes on 31 spline 8.8 are straight, 28 spline axle tubes 'neck down' toward the end. they are larger diameter near the diff.
 
as far as i know its a 8.8 but what do i know tag says s2151 355
2L73 88 9m08
has 355 ford on the gear .

silly ? how you tell the different in the to sizes.
 
inside cover from bolt hole to bolt hole is amost 9 inches 8.8 is that how you do it.

28 or 31 axle


28 or 31 axle
 
do the two bolts on each side of the diff.{bolt size 18 mm] hold the axles in i not for sure just dont want to mess up any thing want to do all my self so i can say i build this truck and thanks guys for all your help
 
Yo,
That looks like an 8.8 to me. I always tell by the shape. A 7.5 is round all the way around the pumpkin, an 8.8 is straight flat on the sides.
 
are you sure the tag didnt say 3L73, not 2L73? the axle probably had 3.73's in it originally....but if the gear says 355 someone must have swapped in a set of 3.55's for some reason

either way its an 8.8.

dont remove those 4 18mm bolts. those hold the carrier in and if you remove that and mix up the shims you'll be in deep doo-doo.

you can determine spline count two ways: the first, like kunar said, is by the axle housing. if it tapers to a smaller diameter just before it meets the brake backing plate, then its a 28 spline. if its straight, you have a 31 spline.

the other (and more definite for those with untrained eyes) way is to pull the axles and count the splines. for this you have to remove the limited slip spring and unbolt the center pin. slide the pin out as far as it goes, push the axles in and pop the clips off. the axles will then slide out.
 
I stand corrected, didn't know there 4 lug 8.8s... Pull the axles and count the splines.
 
Wicked_Sludge said:
are you sure the tag didnt say 3L73, not 2L73? the axle probably had 3.73's in it originally....
Click to expand...


If the axle is indeed from a mustang, it's far more likely that it was 2L73. 2.73's and 3.08's were VERY common in fox body mustangs.

I'm quite sure that all fox-body 8.8's are 28 spline.


What kind of rims do you run on this thing?
 
looks like an 8.8 but unless its bolted in your truck already i'de toss it and get one that bolts in your truck(from a ranger)
 
its 28 spline and yes already bolted up in truck had to put new perches on and weld them up to make it work
 
ok axles off was alot easier than i thought now on this diff. any thing i need to watch out for when takeing it out.buying a set of 5 lug moser axles and a 31 spline diff to go along with it and thinking of getting 390 gears or 410 in instead of the 355 i have wont be driven much on road more track.
 
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