Engineered cover design keeps oil on the gears; Deflects oil back onto the ring gear and into the pinion gear for cooler longer life; Extra capacity sump located at bottom for gears to pick up oil; Internal and external cooling fins; Stainless steel allen head cap bolts, fill plug; Magnetic drain plug; Gasketless cover has integral re-usable Viton O-Ring; Ford (1989-up) with AA12-10.25 or AA12-11.5 single rear wheel differential