There are no aft closures for an AMW motor. A complete motor would include the case, a forward closure/bulkhead, two snap rings, a nozzle washer, and a reusable graphite nozzle. The snap rings, nozzle washer and forward bulkhead are interchangeable between the various casings of the same diameter (the 75mm have two different forward bulkheads depending on case); the only thing that you would need for the next casing would be the respective nozzle and the casing itself.