02 Rear End codes

[blackadder]

I have these tag shots off of the rear in my sons 02 Firebird and another rear he ggot as part of a deal on some rims. Is there a site or any way to decode these to find out what he has? Also the rotor on the rear in his car has a bore that equals the hub but the holes for the wheel studs are larger then the studs. The number comes back as 98 Camaro rotor. Is this normal or is the V6 rear and V8 rear have different stud diameters?

[blackadder]

Here is a pic of the rear rotor. It has a GM part # and is for the car. Another site had a thread about it and it seems that was the way they were made. Car has around 70000 Kms or 45000 miles. Wonder why they did it that way?