Where to get the little chrome trim rings for dash switches on a '70 911???
 

Can anybody tell me where I can get the little chrome trim rings that screw the switches onto the dash. Specifically I am talking about the rings on my headlight switch, rear defrost switch and fog light switch. These rings are kind of pitted and ratty on my recently acquired '70 911, so I was hoping to swap them out for some new ones.

All tips appreciated. Thanks to all!

Wolf