63 - 79 GM-NOS Discontinued Rear End Cap / Product Number: RS316

1963 to 1979 GM-NOS Discontinued Rear end cap. When using Cap on 1977 and prior years. Need to change lower spring plate to GM# 457977 / RS237 and add GM# 459032 / RS315 spacer kit. New GM cover use 7/16 attachment bolts.  Need to Add GM Differential Fluid KIT RS317.  Kit contains 1-GM Posi-Traction Additive, 2-GM Rear axle lube bottles, 1-GM rear end gasket, 1-GM Vent Cap DO NOT OVER TIGHTEN BOLTS, YOU WILL CRACK THE DIFF COVER! GM Cap Part # 464909 Product Number: RS316