My brake rotors on my 2002 GMC Siera P/U were extremely rusty. I had them machined and installed new pads. I am now thinking of the question: Is there a difference between the right and the left rotor. Front to back is of course obvious. Does it matter which rotor goes on the left and the right in regards to front and back? If it does matter, is there anyway to differentiate between the left and right? Any advice would be greatly appreciated.