Those boosters have been unobtainable for a long time. If you order one from RockAuto, Advance Auto Parts, O'Riellys etc.. all you are going to get is a functional equivalent, probably off a truck or van. It won't look anything like the original and won't have anywhere near the power. The stores may have a picture of that Bendix booster, but you won't get one like it.

Best to send yours out to Booster Dewey, the RamMan, or others that offer rebuilding services.