45+ years old and has rubber elements-do they fail? Can't imagine they last forever. I see rebuilding services on the net. Are they "tuned" for specific parameters?

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Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT