Differential type?

I have a 1992 GMC Jimmy 4.3L CPI (W) , 4x4, four door which I had planned to install Positraction no-slip by Powertrax in both front and rear.

Can some one tell me how I can find:
Manufacture of Axle, Axle Model, Spline Count, and Cover Bolts? (other then disassembly)

Do one of you pros know or can I call the Dealer to find this information.

Also has anyone had and experience with this system?

Thanks