Tyler, I think you are referring to the leather primer seals for the TD-20 carburetor. I believe Lloyd Lautner still makes and sells them. If memory serves, the price is now $10.00 per set of two.
His address can be found on the pochefamily.org carburetor servicing section, Basic Carburetor Servicing Johnson H and T Series (pochefamily.org) with instructions to send a s.a.s.e. with the money.
Some have substituted o-rings, for the leather, with mixed results. Best to use the leather seals.