You are looking a GM main case side cover for a Muncie 4 speed. It is cast # 3831707. Correct for 1963 to 65 M20, M21 or M22 in all GM applications including Chevelle, Corvette, Nova GTO 442 and Buick GS. Those are NOT CRACKS, they are casting lines. This piece is in good condition. No cracks, chips or ware. Just clean and use.