Here is a new original stock Dana Differental 488 Ring &Pinion for the 1955 through 1964 Pumpkin type differential that all Chevys had in that era. If you currently have a 411 and want to upgrade to 488 you can use same spacer. This set comes with crush collar required. Makes the quarter mile racer a Winner! This set is absolutely ready to install condition to the knowledgeable mechanic