I pulled my rear drum last night and my rear drum had axle grease inside it. I pulled the axle and the rear seal looked OK. I am going to replace it anyway since I want to put all new brake hardware and shoes and I don't want it to get contaminated. I also looked in my shop maunal and there shows to be a gasket that goes behind the metal plate that bolts to the axle housing, I do not have one and the auto patrts store does not show one available. Is there a gasket that should go on that metal mounting plate that bolts to the axle housing?