The E46 rear driveline and suspension have an unfortunate problem in the rear mounting points for the subframe.  The mounting points can rip out from their spots in the sheet metal. This happens because the rear differential transmits the torsional load from the engine through the subframe, then into the chassis. This constant loading and unloading weakens the sheet metal and causes it to fatigue and separate from the chassis. BMW tried to fix this problem by placing a cross member on the front two mounting points of the subframe. This cross member keeps the front mounting points from having problems by placing the bushing and the stud in double-sheer, thus reducing the twisting action on the sheet metal. The unfortunate side effect of this is that the load from the front of the subframe now gets transmitted to the left rear of the subframe. This is where we have seen many failures of the chassis on low mileage street cars and race cars. We use the Turner Motorsport reinforcement kit that’s been proven over and over again to be very effective, and ultimately a fit for this problem and is also strongly recommended as a preventative maintenance item.