Changed the oil in the rear LS differential (1997 SB , off-road 4x4, auto )and added a whole tube of "Sta Lube " Equa-torque" as directed. But I'm wondering since the LS Differential only takes 2 qts of oil whether I may have added too much and if this could cause a problem?

 

Do you have a book for your truck? Or even the owners manual. You should fill it to the bottom of the fill plug, unless I am wrong. If so how could you overfill it?

 

No such thing as a "Limited Slip" rear differential in any 1997 GM Light Duty Truck.

There is a G80 Eaton Locking Differential and it requires no special additives since it utilizes no clutches.

 

Well it sure doesn't lock. Does that mean its worn out? Seems to lock better with the additive. But maybe I should drain and replace with no additive?

 

Are you sure that your truck is equipped with the locking rear axle option code G80?
Most were not.

If you placed the additive in fresh gear lube it will not harm your rear end but synthetic 75w90 is highly recommended and what all new Silverado's are shipped from the factory with since 1999.

 

Its the "off road 4x4". Where on the truck would I find that info?

 

I have a 2005 chev 1500 crew cab with locking rear end, that slipps on occasion is has 50,000 mi what can i do for it. does it have clutches

 

When you open the door of your glovebox you'll see a "Service Parts Identification" sticker with about 2 dozen three digit alpha-numeric codes.

A thread search here at CF should give you a post which deciphers these codes.

 

Why am i looking at these codes, the window sticker says it has a locking rear gear 3.23 ratio. 2005 2WD 1/2 ton crew cab with 5.3

 

When does it slip? they are locked or open, and disable above 10 or so MPH. if you go around a corner and nail it, it will light up one tire if your moving already, if your going slow it will lock in and hold. When they slip they either make a grinding noise or parts come out through the cover when the lock tab / weight breaks off.
read up on how the G80 locker works. I have 50k miles of towing and offroad hell on my truck and the locker works the same as the day it was new. Its useless above about 10mph - maybe less.