Gear oil Q's ('91 XJ)

This may sound like a goofy question, but I'm going to ask it anyway.

My '91 XJ (recently acquired) has almost 192K on it and is equipped with the tow package and limited slip rear in a Chrysler 8.25 rear end. I'm in the process of changing out all the fluids and am wonder what I should put back in the rear end. The manual calls for 75W-140 synthetic. I'm not sure how long it has been since the gear oil was changed in this Jeep so I'm wondering if I should use the recommended synthetic fluid or not. Could it have any detrimental effects if the current fluid has been in there for a long time?

What do you all think?

Thanks.

Use the synthetic. Seeing as you have a limited slip, you'll also need to add a tube of friction modifier, available at your friendly, local, Jeep parts pusher counter.

. . . and, unless you know that it has been rebuilt at some point in the past 192,000 miles, it's highly unlikely that the TracLoc Limited Slip is still working. If you're in a hurry and don't have the time to check it out and possibly replace, just put in standard gear oil for now. Save the synthetic and additive for a functioning limited slip.

Rebuild kits are not that expensive.

Further info:

http://www.naxja.org/forum/showthread.php?t=5915&highlight=limited+slip

Mike in NJ atriot: