This is everything I have learned about the different types of Borg Warner Rear Ends for our third gen camaros. The factory disc rear diff is something I have wanted and I did some research on what was the best one. The one with the Aluminum PBR brake calipers and 11.6" rotors is the best.
Here are the backing plates: http://flynbye.com/catalog/i31.html

3rd gen camaro
third gen f body
82-92 camaro
Iroc-z
camaro RS
82 camaro
83 camaro
84 camaro
85 camaro
86 camaro
87 camaro
88 camaro
89 camaro
90 camaro
91 camaro
92 camaro
third gen camaro