Locking Rear Axle?

Hi. I'm still learning my 'new' 99 4-door, 4WD and have more questions. The owners manual mentions a 'Locking Rear Axle' but mentions it as if it's an option rather than standard equipment. Is it an option? How do I know if I have one? What does it do or not do? I have push button 4WD and auto 4WD.

Also, the interior rear-view mirror that's in my truck is not the same as the one shown in the manual, and I don't think it works. It's supposed to be some kind of aoutomatic sensor type but like I said, not the same as the one in the book. Any idea what it might be and why it's different?

Thanks in advance!

Chris

Call your local Chevy service shop and they can look up your vin and tell you the options it came with. I beleive they use a limited slip and not a full time locked rear axle. Do you have factory skid plates underneath, if so there is a good chance you got the limited slip with the offroad package.

You should be able to tell by the glove box codes also if you can find somewhere that gives them to you. I've searched the net before and couldn't find anything.

Chris,

On your glove compartment door is a label that lists all RPO's (regular production options) that your vehicle is equipped with. Look for RPO G80 which is the code for the locking differential. It basically transfers rear wheel power to the wheel that has the most traction. If one wheel is on ice and the other is on dry pavement, a clutch mechanism inside the rear differential drives the wheel that's on the pavement instead of spinning the one on the ice. This option has nothing to do with 4 wheel drive which also directs power to the front wheels through a transfer case.

Thanks guys. I've got G80. So 'Locking Rear Axle' is just another term for limited slip differential? I found the code definitions here:
http://www.jcscoops.com/faq/rpo_1999.php