Kevin- Get the number off of your axle then go to this link & look at the listing under "Rear Axle Codes". The first two letters are the key; http://www.camaros.org/drivetrain.shtml#AxleCodes
. It will tell you exactly what you have. Here is a pic of mine to use as reference;
Your POP says it's "PL" which is 3.55. So you are probably correct. Just verify it with what's on your car.