4mm, those appear to be vacuum motors for the hot air door in the air cleaner snorkel. Most of those had had a tab that slipped into a matching slot and were held on by a single rivet. Ford never released a service part number for the ram air motors. They were part of the actuator assembly which included the motor, plastic housing and flapper door. At one time NPD sold reproduction motors so you could service the 71-73 ram air actuators. From what I understand they are no longer available and are extremely difficult to find. The original motors have two mounting ears and are held on by rivets.
There is a process where the the vacuum diaphragm is harvested from motors like you have and modified so they may be used to repair the ram air motor. Around May of last year rackerm had an excellent write up on how to perform such surgery. https://www.7173mustangs.com/thread-hood...ight=EC514 (See post #5)
The illustration is a original actuator which shows the vacuum motor and how it is attached to the housing.