It uses the same gasket as the cover. They are pretty thick. You will probably have to buy the whole gasket set but if it comes without the seals it should,t be expensive. I don,t know about the backlash but I don,t think I would put it on with just RTV for that reason. If you use a thick gasket you should be OK. Napa Or Carquest should be able to supply the complete set or you can make one out of gasket material.