The element is no longer available in the US. Made to last and the replacement market failed to materialize. It was made of a special material Skinner had patented. It's a helically wound cellulose fiber element. Now completely obsolete here in the USA, it's now made in Japan by Fuji
Stock gasket is cork: 2.13" OD x 1.8" ID x 3/32" thick. A smaller ID won’t fit properly.
Felpro gasket part #773 is a bit tight at 2.16" OD, but does compress in to fit.