Came across this....
www.garagistic.com
E9 and E10 Adjustable Rear Subframe Conversion - 2002, CSL exclusive
E9 AND E10 ADJUSTABLE REAR SUBFRAME EXCHANGE PROGRAM The stock E9/E10 rear subframes does not allow you to align the rear wheels. This problem carried onto future subframes like the E28 and the E30. Alignment is a critical point in how your car handles and wears tires. Especially important in...