I've been having a couple of noises in the rear of my car (o1 Z28 A4 3.23) that I need help with. The first is kinda easy. When ever the car is put into gear, I hear a "ping" sound. U-joints are new. The Chevrolet guy I talked to said suggested I drill two holes in the driveshaft and fill it with foam. I have no problem doing this, but where should I drill, what size should the holes be?
My second noise is coming from the rear end. I've been told that it probably has the wrong fluid without the additive GM suggests. I just changed my rear end fluid today and I was wondering if this was the problem, how soon will the chattering go away, especially when turning. I put in Mobil 1 Synthetic 75w 90 with a bottle of GM limited slip differential additive. Any advice would be appreciated. Also, does anyone know of a place that sells steel LS1 driveshafts?