Most tappet chest covers use the 12A1175 rubber gasket, but early covers with flat flanges require this cork gasket. Also check 12A1176 seal and 12A1177 cup washer for the tappet cover bolts when doing this job. Sold each, two required.
Important: If you are looking for a valve cover gasket, see GUG32VC. While these two gaskets are made of the same material (cork) and are similar in shape, they are not interchangable!