I have developed a leaking rear brake chamber and need to replace just the diaphragm. I have found only one post that lists the size being a type 9 for the service and a type 12 for the parking. I have called a few truck service centers and they don't carry those sizes. Also while looking there seem to be many different options for those sizes. I am not very familiar with the air brakes systems and the different diaphragms but if anybody has more info on them that would be great