2002 Silverado 2500HD Rear Axle Removal

I have a 2002 Chevy Silverado 2500HD Extended Cab Short Bed 2 Wheel Drive with an 8.1 Liter V8 and an Allison 5-Speed Transmission. Mileage:68,000. I need to change the right rear axle seal as it is leaking. I have the Chilton manual and was following their instructions. When I removed the Hub cover on the wheel I found that the axle end is completely different than they picture. It has 8 3/4" bolts around the axle end. Do I still need to open the rear end cover with this type of axle? Can you tell me where I can find detailed instructions for this procedue?
When I bought the seals the Chevy dealer said it was an 11 1/2 inch rear end and the axle number was AY8. Hope this is enough info.

Thanks