Call up kirban or check out there website. They sell the gasket with the block you can get it in aluminum also. Fairly cheap. Check out there website and email them they will send you a free catalog.
Shhh!!! Don't tell anyone, but I made one out of cereal box cardboard...Just traced the old cracked one onto the cardboard and cut it out and bam!!! One vacuum block gasket!!!
For christ sake if you need to make one just buy some da#n gasket paper. You can get it at most reputable auto parts store and just trace it to the CEREAL BOX METHOD!