Has anyone shimmed the rear selective washer that sets the clearance for the rear endplay? If so, what material did you use? I have some sheet aluminum that I might be able to cut and shim under the washer. I ordered some rear selective washers from a transmission parts house and they sent the wrong sizes (ordered #5,#6 and got #1,#2 -- all too thin). I need to tighten up about .020" over the current washer. I am tired of ordering, waiting and receiving the wrong parts. I prolly should contact the vendor to make it right, but I am going to have to wait again dammit. I am going to order from the local GM dealer today. Hopefully they can get it right.