Spohn Suspension - 93-02 F-Body - 10 Bolt (7.5") Rear Support Cover Six tons of support for your differential! GM 7.5" 10 bolt rear-end support cover: Our rear differential cover is not only tough, it's cool looking too. Cast from premium 356 aluminum and heat-treated, the heavy duty cover comes with hardened bearing cap support studs, ARP stainless steel 12-point cover bolts, a magnetic 3/8 in. fill plug, and a gasket.