cam bolt and washer

OK, you small block guys. Where can I get the washer that retains the sprocket to the cam? The bolt is not an issue, but it seems the washer is made of unobtainium. This was used up to 2005 on the small blocks, but is NS-1 from the dealer, and I have been unable to find an aftermarket source. The same bolt/washer is used on the slant six.