IMO those paper diff gaskets are obsolete. Just squirt a bead of RTV around the cover, and be sure to make a circle of RTV around each bolt hole. Anything Permatex brand is a good bet.
1951 1/2 Ton 216ci 4spd 1955 3/4 Ton NAPCO 235ci 4spd 1959 1/2 Ton stepside 235ci 4spd