This power brake booster will fit the 66-71 Jeepster Commando. It can be used as a replacement of an existing booster or it can be used to upgrade to power brakes. This booster will bolt directly up to original power brake brackets or we offer new brackets for those that did not originally have power brakes. We offer several different master cylinders for this booster. The preferred master cylinder that we sell is the 1″ bore master, MC1321H, it can be used in disc/drum or drum/drum configurations. Zinc Chromate finish, 3-3/8″ Bolt Pattern (Firewall Side), and 3-3/8 Center to Center Bolt Hole (Master cylinder Side). We have many configurations to offer so please call if you need an entire power brake system.