ok, i guess no one seems o have a sure fire way of knowing? so wtf do yall do when you put oil in your rear diff? go ahead and put the additive in to be safe?? i don't want some half *** way of testing for it.

 

Then call the dealer ask them for a build sheet on your truck and that will tell you, unless someone changed the rear before you got it. Or just go ahead and use Valvoline 75w140 synthetic which already has enough additive in it for Dodge's, not enough for Fords and Toyota's though.. Its an ideal weight gear oil for extremely cold temps and heavy duty towing..

 

I believe when you remove the diff cover to change the oil you will see the difference.
Clutch packs on the LSD and just beveled spiders on the open.
Get the additive and if you don't need it return it.

 

shoot, i came into this thread thinking you we're talking about drugs haha. guess not.

 

LMAO!!!!

 

yeah i guess calling the dealer would be the best and has been the best option. if i knew what clutch packs looked like inside the differential i'd be good to go. either way i'll give them a call monday to get this squared away asap.

 

The test is really simple, I don't know why you guys are having so much trouble with it. Jack the back of the truck up with it in park and 2wd (if applicable). Try to spin a wheel, if it spins and the other goes the other way you have an open diff or a really wore out LSD. If you can't spin it you have a LSD. If they both spin the same way or only one spins something is broken or you're not in park.

You want to be 100% sure, pull the cover and look.

 

Perhaps I wasn't specific enough.

In park, with an LSD, rear end jacked up, the wheels shouldn't turn, if one does though, the other should turn in the opposite direction.

 

i'll just call the dealership...quick and simple.

f*ck it, i'll just jack up my truck and play spin the wheel. who knows, its a 50/50 shot. (sarcasm)

 

Corporate 9.25 LD in the rear

okay, does this tell us anything different that we didn't already know?