I was coming off the track yesterday after a 20 minute session and once I slowed down I could here the rear differential making more noise than I thought it should. Almost like a clacking sound as I was driving a steady state at about 5 mph. I just recently re-installed my cats so the exhaust isn't anywhere near as loud as it used to be. I guess the rear has always done this but I am just now being able to hear it. Once the rear cooled down it was business as normal. I checked the oil level, FOMOCO rear end fluid, and it's fine. I was wondering if others experience this as well?