im sure if you called the dealer that they could ship you some, or go into your local auto store and explain to the guy what you need, equivalent to mopar friction modifier

also i have heard (double check on this please) that some synthetic diff fluids come with a friction modifier in them which is acceptable(i believe mobile 1), but please check on that so you dont have any problems if you decide to go that route

 

Just wanted to thank yall for your help. Thanks to this forum I spent the day servicing my D. I removed and cleaned the throttle body and IAC (it definitely needed it!), tranny fluid and filter change and band adjustment, transfer case fluid, and front and read diffs (with FM for the trac-lok rear). It only took 8L ATF+4, 4L full synthetic 75W90, 1 tube friction modifier, 1 tube permatex red silicone, 1 burnt forearm, 2 skinned knuckles, and 1 medium sized goose egg on my forehead.

It was all worth it though. She idles much smoother and shifts better now. I'm going on vacation in 3 more days and I'll be towing a 19' travel trailer up & down mountains about 850 miles round trip. I feel much better having everything tuned up. All I have left to do tomorrow is find a spot to mount my brake controller and start loading gear!

Thanks again for a great forum!
Colin

 

Glad to hear!

You need at lease 5oz of friction modifier in the LS rear end. I go to Auto Zone and get a 7oz bottle for $4.99 and use the entire 7oz then top off with Mobil One 75W-90 LS Fully Synthetic Gear Oil. Now Mobil One 75W-90 LS Fully Synthetic Gear Oil is already rated for use in LS (Trac-Lok) Differentials and Open Gearing Differentials but still use the extra 7oz of friction Modifier.

If you have an open rear end then you do not need the friction modifier. To find out if you have a LS or open gearing please do this:

Lift both rear tires off the ground and turn one of them. If the other tire turns the same direction then you have a LS (Limited Slip) Rear Differential, if it spins the other way then it is a Open Gearing Differential. It is easily lifted by placing a floor jack under the center of the rear differential and both tires will be lifted. Remember to chock the front wheels to keep it from rolling on you because there is no gears to stop it from rolling!

 

HS- I did the same as you and used the whole 7oz tube of FM and then filled with synthetic 75-w90. I did the wheel spin check first to make sure I had the trac-lok diff. (I do) Aside from being a beeyoch getting the top bolts out of the front diff, the rest wasn't too bad. I think I'll invest in a couple of pairs of ramps though, as just using the jack stands doesn't give you a lot of room to move under there, even with a creeper!

Thanks again!