How do I fugure out which axle it is?

[84jeepj10]

I have an 84 J10 w/AMC 360. The markings on my rear axle are stamped on the top of the diff housing:
428 (BIG letters)
249 (smaller and circled)
1A3235428 (the A is circled)
The rear axle looks solid with 4 bolts connecting it to the drums on the wheels on each side.
The front has no markings and are connected at each end by U-joints to the wheels.
My vin only states that I should have a NP208 transfer case and my Haynes manual says that these things came with either dana 44 or dana 60 axles and some with LSD. Please help me figure out which axles I have.

[joe]

First things first.... put the Haynes back in the outhouse for emergency "domestic" use where it belongs.
The rear axle on the 84 J10 is an AMC20. Only the J20's from 74(first J20) got D60 rears. Also no J10's since 1979 have D44 rears. Ok maybe the 87 J10's(?) but that doesn't apply here anyway. The front is a D44 though.
The M20 has a round smooth cover where a Dana cover will have a protrusion for the ring gear as on the front differential.
The axle code for the ratio is stamped into the boss next to the dowel hole on the cast part of the pass side of the housing. 2.73 axle ratio will have the code "D" and 3.31's will be "B". If the letters are doubled it has a trac-lock LSD from the factory.

[84jeepj10]

What I wrote in my origional message was ecactly what was stamped to the top of the diff housing and how it was stamped. So what does a AMC20 have for me compared to a dana 60? Better/worse, stronger/weaker. And how would those gears be for a huntin rig that's still a highway driver? thanks for the info.

[J10Mike]

84,
the amc20 is a 1/2 ton axle. the d60 is a 3/4 ton axle. the amc20 is a good axle and should be plenty for trail as well as highway. of course, the d60 is a heavier and better axle to have.
if you can't find the gear ratio from the rear, check the front d44 tag. as joe said, it should be 2.73 or 3.31 for the tow package.

mike

[J10Mike]

84,
post a pic of that beast. or, send to my email.

[joe]

A D60 is a lot tougher than an M20 but the M20 is as good as/comparable to a D44 used in the pre-80 J10's.

[84jeepj10]

Which years of the wagoneer came with D60s and how do I tell the difference? I know a local salvage yard that's got 2 Wags, I've already salvaged a wire harness and rotors from one of 'em so I know it's got a d44 up front. Thanks.

[joe]

No Wag ever came with a D60 rear. Even if they did it'd be about 6"-8" narrower than a trucks axle. For your 1/2 ton 84 J10 unless you want to change front axles and trans/tcase also you're limited to a J20 from 80-87 or another brand 3/4 or 1 ton truck donor that has the rear diff centered. Pre-80 3/4 ton Jtrucks have the diff offset to the pass side as is the front diff where your trucks diff is centered in the rear and the front is drivers side.
A D60 will have the model number cast into the gusset/web closest to the diff case.

[Torque]

The only way to know the ratio and if you have LSD is to open up the diff.My AMC20 was stamped B which indicates a 3.31 open diff,I have a 3.73,LSD

www.off-road.com/jeep/tech/axle/amc20.html (http://www.off-road.com/jeep/tech/axle/amc20.html)

[Joe Guilbeau]

AMC Corporate 20 Rear Some J-10's Axle: http://www.jeeptech.com/axle/amc20.html

Dana 44 Rear Axle Some J10's:
http://www.jeeptech.com/axle/d44.html

Dana 60 Rear Axle Most all J20's/some J10's:
http://www.jeeptech.com/convaxle/d60.html

Various differential covers:
http://www.offroadunlimited.com/new/parts/diffs/

[joe]

Originally posted by Joe Guilbeau:
Dana 60 Rear Axle Most all J20's/some J10's:
http://www.jeeptech.com/convaxle/d60.html
Just beware that the above link is for a D60-2 semi-floater axle and was dropped in 74 so it won't be found in any J10 or J20 but only in the previous J2000/3000/4000 trucks

[84jeepj10]

Thanks Joe Guilbeau for the links. According to the code for the AMC20 wide and short trac I can expect to have (stock) 3.54 ratio and open (that sucks) diff. Provided it's all stock. I have know idea howto properly dismantle the diff to find out. Do I just take off the cover plate? Or is there more to it than that, and once I get in there what am I lookin for?

[joe]

The only gears avail from the factory in an 84 J10 were either the stock 2.73's or optional 3.31's. If you have 3.54's in yours then they were installed later by a previous owner. To know for sure what you have count the teeth on the ring gear and divide by the teeth on the pinion gear.

[PlumCrazy]

Ok so if I stick my head under my 71J4000 then I would find Dana 60's under the rear and 44's in the front???

[84jeepj10]

The markings on my rear axle are stamped on the top of the diff housing:
428 (BIG letters)
249 (smaller and circled)
1A3235428 (the A is circled)

Is that last number with the letter A circled where I get my code from? If so then the A would mean 3.54 gears, could that mean I've got an axle from a J20? Or just one of the few J10s they made w/those gears? I think the more I'm gettin into this the more I confusing myself, hopefully it'll all make sence in the end.
This is off the first link:
Narrow Track AMC 20
Code Gear Ratio Diff Type
AA 2.73 Open
DD 2.73 Trac-Lok
BB 3.31 Open
CC 3.31 Trac-Lok
A 3.54 Open
N 3.54 Trac-Lok
GG 3.73 Open
Q 3.73 Trac-Lok
L 4.10 Open
M 4.10 Trac-Lok
Wide Track AMC 20
Code Gear Ratio Diff Type
D 2.73 Open
DD 2.73 Trac-Lok
B 3.31 Open
BB 3.31 Trac-Lok
A 3.54 Open
AA 3.54 Trac-Lok
H 3.73 Open
HH 3.73 Trac-Lok
C 4.10 Open
CC 4.10 Trac-Lok

[joe]

Originally posted by 84jeepj10:
The markings on my rear axle are stamped on the top of the diff housing:
428 (BIG letters)
249 (smaller and circled)
1A3235428 (the A is circled)

"Forget" the numbers on top of the axle housing. As I said in an above post regarding the axle ratio code for an M20:

"The axle code for the ratio is stamped into the boss next to the dowel hole on the cast part of the pass side of the housing. 2.73 axle ratio will have the code "D" and 3.31's will be "B". If the letters are doubled it has a trac-lock LSD from the factory."

[joe]

Originally posted by PlumCrazy:
Ok so if I stick my head under my 71J4000 then I would find Dana 60's under the rear and 44's in the front???Depends on what version your J4000 is as to what your rear axle is.
If it's the 5000 GVWR J-4500 you'll find a D44 rear. If it's the J-4600 w/6000 GVWR you'll se a D60-2 semi-floater. If your truck is a J-4700 or J-4800 you'll find a full-floater D60 back there.

[joe]

84jeepj10 check your email. I sent you a picture of where to look for the axle code.

[84jeepj10]

-joe: Thanks for your help. I finally found it (B). I had to scrape away some mud but I found it lol.

Now how do I go about opening up the diff to double-check what I have? Is there some special mojo I gotta put on it first or do I just remove the bolts on the cover and there it is? Which gear will be which? Thanks.

[Torque]

Mine had a 'B' on the axle but when I opened it up I found 3.73-1 and LSD.
As for opening it up it is pretty straight foward put a large pan under the diff and loosen all the bolts.When the seal is broken the fluid will run out wait till there is no more before removing all the bolts.It helps to drive it first to warm up the fluid.