hi all in my1988 MM i have a G63b.. recently went to replace valve cover gasket.at the back of head there is a half moon rubber grommet. did not come with valve cover gasket replacement.. where can i get one of these. it is hard as a rock.. also where can i get the rubber grommet washers for the top of valve cover where the nuts are... are those dealer items?? thanks for reading and your time.