What do I look for to tell which rear axle I have? It's a 90 2dr 4x4 XJ Laredo and the axle has a rubber fill plug. I need to know which one I have and if I'm supposed to use a friction modifier when I change the gear oil.

The bottom edge of an 8.25 is flat. The Dana 35 is round. 5 bucks says you have a 35.

So, did I win 5 bucks?

Most likely dana 35

If he has ABS then he has a Dana 35. If he doesn't have ABS then he should have a 27 spline c-clip 8.25.

did 90's even come with ABS or an 8.25? Sorry for the jack.
OP: Where are you at in Rome? not to far from you down in Carrollton

Yes.

Oh ok i thought they started in 91 lol but i didnt know about ABS.

Yes, 90-2001.

The rule of thumb about ABS applies. Typically. Not always.

What was pre 90? I know the D 44 but what else

More than likely the "wonderfull" Dana 35. Does it make so much noise it drowns out normal conversition in the jeep on the highway?

Ga crowd is up in here lol polk aint too far either

To answer this question...you don't need any additives unless you've got a limited slip, which i doubt you do.

TO check jack up the rear end (after you block the front tires), put in in neutral, and spin the rear tire. If the other rear tire spins the opposite way than your turning, its open. Same way, Limited Slip.

Very impressive chart lowrange2. I went out and took pictures of both axles but, the drawings were a little too non-descript so I went surfing for actual photos.
The front is a D30 for sure.
As for the rear, the D35 and Chrysler 8.25 look almost identical and both even have the rubber fill plug but, mine has a long metal tab on a cover bolt on the bottom left corner. The pictures I found on this page....
http://www.lunghd.com/Tech_Articles/...and_Ratios.htm
would indicate that it's a D35.?
I also remember reading somewhere that some D35's are open diff's and some are limited slip.
I guess I'm just going to have to pull the cover to find out for sure.