'65 Power Brake Booster Question

I believe Ulf @65dartcharger researched this and found those late 50’s Caddys used the same booster. Maybe he’ll chime in on that and your issue on the torn rubber.

Agree with @Big_John on his evaluation of the internal booster rubber parts and sending it to Booster Dewey to get rebuilt.

I assume you have the vacuum storage tank that is required with that booster?