So I came across a web link with some great  information. I’ll leave a link below. This website tells you all about maintenance intervals and fluid amounts etc. I plan to change my diff gear fluid soon and I plan to use Scaeffers 75w140 gear oil. Iv heard  talk about adding a friction modifier? I’m curious if anyone knows about this stuff and how much is needed per axle? http://www.cumminshub.com/5.9-24v-cummins-maintenance-schedule.html

Edited August 16, 20186 yr by Marcus2000monster

You only need the 75w-140 and friction modifier if you have limited slip rear end. If you have the standard open differential like myself then you want standard 80w-90 gear lube and on friction modifier. Axles should be changed every 30k miles or if the fluid is darken. 

Edited August 16, 20186 yr by Mopar1973Man

IF you need friction modifier, 10 oz of Ford friction modifier is what you want.  It seems to act the best.  None for the front as it is not a LSD.

You can use 80w-90 in the front to reduce drag. Since 75w-140 is much thicker.

Just to point out that the Cumminshub website is not affiliated with Cummins in any way.  Its just another website with collected data which may or may not be accurate.  So use your best judgement on what it tells you...

How can I tell if my a lrefund is LSD?

Go Here , select equipment listing, and enter your VIN.

Edited August 17, 20186 yr by Imaybail

You can also decode here but I'm not sure it gives all the specific package component details.

 

Usually there's three methods to identify a LS differential:

1) There should be a sticker on the inside of the glovebox door which lists build codes.  You're looking for the one that says anti-spin diff.

2) You can jack up the rear axle off the ground and with the transmission in neutral and the e-brake off, spin one rear tire by hand and see what the other side does.  If the other tire follows the same rotational direction then you have a LS carrier.  But if the other tire spins in the opposite direction then you have an open carrier.

3) You can pull the differential cover off and look at the carrier.  If its a LS then there will be clutch packs on either side of the spider gears on the axles and there should be a curved spring pushing out on in the middle.  If its an open carrier then there will be none of that.

Edited August 17, 20186 yr by KATOOM

Dodge guy told me I've might what was called "corp axle".  And if I understand him right, Chrysler used Dana housing, but had Dana dummy down their product.  Guy said the "M" might be "M" as in  Modified and not a true dana.  Is my understanding right? I do know I get stuck very easy unlike other 2 wheel drives I've had. But stuck real easy.  

 

Glove box sticker says

Dana M70/26

Anti-spin differ

Edited August 17, 20186 yr by 015point9
Add info

9 hours ago, trreed said:

IF you need friction modifier, 10 oz of Ford friction modifier is what you want.  It seems to act the best.  None for the front as it is not a LSD.

I have bought the mopar stuff from genos in the past. Ford friction modifier works better? Doesn't really matter as long as the lsd works as its supposed to at the end of the day. Thanks for the heads up. 

1 hour ago, 015point9 said:

Dodge guy told me I've might what was called "corp axle".  And if I understand him right, Chrysler used Dana housing, but had Dana dummy down their product.  Guy said the "M" might be "M" as in  Modified and not a true dana.  Is my understanding right? I do know I get stuck very easy unlike other 2 wheel drives I've had. But stuck real easy.

 

Yeah, the axles under these trucks are "Dana" but only the inter components.  The housing was built by Dodge (or some third party contracted by Dodge).

1 hour ago, Dmaney said:

I have bought the mopar stuff from genos in the past. Ford friction modifier works better? Doesn't really matter as long as the lsd works as its supposed to at the end of the day. Thanks for the heads up. 

Sort of friends with our Ford parts guy.  (Thanks to a 03 f-350)  I was surprised when he told me who they sell some of their fluids to.  Limited slip and their racing grease used in many applications besides ford.

I have their stuff in my 01 dodge.  No problem.   Whatever directions say to use PLUS 10 percent is what I use with a Dana 70 and mag-hytec cover.  But I would use what ever you have on hand first.  

 

Some auto parts are sort of strange, if not actually in the business.  When I got new injectors for my 5.4 Ford.  He told me to go to napa, "same thing as Ford but much cheaper".  But most mechanics at his place hate the Ford silicone goop and prefer off the shelve ultra black.  But Ford's silicone valve in oil filters are supposed to be better than other brands that need a valve built in....and probably a lot of snake oil mixed in?.

 

At my location, Geno's is usually 5 days away for me.  While I like Geno's, I'm ordering less and less from them.  

Edited August 17, 20186 yr by 015point9
Add info

286RBI is the Dana 80

Also note the procedure with the figure-eight turns...if you do find you have the limited slip option.

Edited August 17, 20186 yr by sooxies

Most, if not all, synthetic differential lubricants already have friction additives in the recipe.  So depending on the fluid you choose, dont go adding more additive unless you have to otherwise you'll end up with a LS which does nothing.  The factory LS is already set with a low preload for more friendly driving characteristics so you dont want to make it any less effective.

15 hours ago, Marcus2000monster said:

How can I tell if my a lrefund is LSD?

 

Glove box sticker and axle tag (little piece of alum secured on diff cover) and vin look up.  After confirming, then I knew I should add friction modifier. Other people could probably tell by looking at inside, but not me.

15 hours ago, KATOOM said:

3) You can pull the differential cover off and look at the carrier.  If its a LS then there will be clutch packs on either side of the spider gears on the axles and there should be a curved spring pushing out on in the middle.  If its an open carrier then there will be none of that.

Dana Trak-Loc is set up different.  You won't be able to see the clutches, as the carrier is a covered case that splits in half, and there isn't a spring.  You will only be able to see the end of the cross piece that holds the 4 spider gears. 

Trac-loc is in the Dana 80

Power-loc is in the Dana 70 (and what you pictured)

 

If Marcus2000monster has a factory LS then its the Trac-loc.  Either way, you should be able to see the spiders and clutches in the side holes.  Its been a long time since I remember looking at mine though so maybe the spring isnt there...

Edited August 17, 20186 yr by KATOOM

You are correct.  Moving too fast and grabbed the wrong picture.  But, he won't be able to see the clutches on the trac-lok either.  I'd be surprised if he could see the side pinions.  I couldn't when I had my carrier out recently.

But I can see them in that picture you posted...  Well not perfectly because of the angle but definitely if it was in person.