jiggie

Hey everybody I have a 95 grand Cherokee Laredo with the straight six and MP 231 transfer case. I'm wondering how I would know if I have a limited slip rear differential or not. Getting ready to change up my fluids I need to know if I need to buy the limited slip additive or not. Also what does everybody think about adding the Lucas oil stabilizer to your differentials

dave1123

Put the rear end up on jack stands or lift, turn one rear wheel. With an open differential, the other wheel will turn the opposite way if the trans is in park. With an LSD, it won't turn or turn VERY hard. In neutral, they both turn the same direction with an LSD, opposite with an open one.

A "Friction Modifier" or LSD additive is good whether you have one or not. I'm running Valvoline 75W-140 Synthetic in my open D35 because I load it up with newspapers 3 times a week and drive it in the snow that way. It has an additive in it, but not enough that an LSD needs. It has 200K on it, 75K with me, and it still doesn't whine or complain.

BTW, I've had 1500 lbs in it and the 4.0 doesn't care, braking is a little slow when it's that heavy however.

andrewmp6

Did you swap t cases ?

dave1123

I doubt he's the original owner so anything is possible. On the other hand, back then you could get a jeep assembled with whatever options you wanted on the factory order. AFAIK, the LSD rear axle was only available on 2wd models anyway.

What Andrew is saying is the usual t/cases in ZJs are NP249 Quadratrac, and NP242 Selectrac. The NP231 was in XJs.

jiggie

No mine came stock with the 231 and unjoint front axle shafts. If I'm crawling up on a rock and one rear spins but the other doesn't not lsd right?

dave1123

Keyrect!

andrewmp6

Stock you have a np242 or maybe a np249 ,The np231 was only used on a inline 6 93-94.If you had a xj then it would be a np231 maybe you got that mixed up.

extrashaky

Yours has a Dana 35 rear axle, correct?

If it's a Dana axle, look for the axle tag. Limited slip axles have either "LS" or "L-S" stamped into the tag in either the upper right or lower right corner. You can also copy down the Bill of Materials number (BOM) and look it up in the Dana Expert website.

Look at this site to see examples of the Dana axle tag and where to look for the limited slip notation and the BOM:

http://www.differentials.com/technic...identification

I linked it in the paragraph above, but just in case you missed it, here's the Dana Expert:

http://www2.dana.com/expertforms/deabill.aspx

Enter your BOM, and it will tell you the model, gear ratio and any special features of your specific axle.

jiggie

Lol no I'm not confused. It's a 231 and no it's not been swapped. According to Jeep they only made 568 grand Cherokee with the 231 t case. Out of those 568 200 had the ujoint front axle shafts in the 93-95.

andrewmp6

Crawl under it and look for the round metal tag on the t case they will id it for 100%Going by jeep no 6 cylinder after 94 had a np231.

jiggie

Ok guys here is a pic of my t case. I'll post my build sheet as soon as it gets here.

dave1123

Yup, built April 3, 95 on 3rd shift. 2.72 low range gearing. They are forgetting the original purchaser could have it built any way he wanted. Like the LSD was only available in 2wd models, unless you ordered it special.

I live about 15 miles from the plant that built that t/case. I knew a guy who worked there. For 20 years, all he did was cut the 1-2 slider gear for the 5-speed truck transmission. BORING!!!

jiggie

Here is my build sheet. Stock 231 t case and d35 rear end.