Alright so their was nothing in my glove box but the build sheet puts me at 3.55 with anti-spin. Consulted the 50000000000 page service manual and it lists both LSDs for 8 1/4 and 9 1/4 inch rear axles as clutch based and needing a bottle of mopar limited slip additive with the gear oil change. Going to get a bottle of that and put the gear oil that's been laying around for ages in whenever it stops raining. Not going with Sawfish's advice of valvoline synthetic because I've had the the royal purple 75w140 laying around for months waiting for the diff to get some attention.

 

"Corporate" just means it's a Chrysler differential (as opposed to, say, a Dana). It has nothing to do with whether or not it's a limited-slip.

 

Tom is correct. If your build sheet does not say "anti-spin" then you have the open rear end.

As a general rule of thumb, if you have the V6, you have the 8.25 rear axle. If you have the V8, you have the 9.25 rear axle.

 

Or try jacking up both back tires and spin passenger rear forward . If driver side rear spins forward then lsd if it spins backward then open.

 

my 2001 dak 8 1/4, factory chrysler paper manual calls it a trac-lok my 1967 factory chrysler paper manual calls it a sure grip differential. the 8 3/4 axle.

 

Ya the service manual for the 2005-07 Daks refers to the limited slips as trac-lock as well.