I see tons of after market stuff for Rugar 10/22 but I have never seen any for a Marlin .22 Why ? My stock marlin will out shoot any Rugar at the range.

Marlin makes so many different models of .22's that it would be difficult to keep up with all of them. The Ruger 10/22 has remained the same in design for many years. It is way more popular than most any Marlin .22

You might want to try Gun Parts. I'm not sure what their internet address is, but you can find one of their adds in the back of most gun mags.
They have just about everything!