I found a place that strives to keep your old stuff running. It's way up in the U,P of MI and they strive to get OEM gasket kits and if they cannot order them direct, they will make them. I had an old Echo weed eater and after I gave him some numbers the owner said to look on the other side of the carb body and tucked way behind a low spot, I found what he wanted. They made the rubber part and I had it in three days. The company is called Discount Marine and they specialize in old boat motors carb kits clear back to when I was a kid and i am 71.
The website for the chain saw and related stuff is dicarbs.com, This guy is older than me and still answers the phone to help you out, He called me back with a price on my made to order part within the hour and got my OK to add it to my previous order. I figure that buying USA neoprene rubber seals and diaprhams is worth every penny and the stuff will actually fit..I cant wait to hear my old made in Germany Stihl run again.