Besides my RB67 I've also used my old Asahi Pentax once again last year. Besides some issues with the mirror which were solved with a drip of oil (mechanical camera's! ;) and the fact that the battery for the light-meter are no longer sold it still worked fine.
As the model is from 1963 (and the camera was at least 3th had when I bought it around my 12/13th birthday) it's as old as I am and still going strong.. Like it's owner..;))
Asahi Pentax Spotmatic, 50mm/1.8 on kodak tmax 100