By the time I got my '75, any of the covers were gone. I know at one point there was a cover over the bridge based on holes in the body, never spotted holes for a cover over the pickup. When did Fender stop with the chrome covers as a standard offering, assuming the covers were something that had come on most everything.
Fender stopped installing the chrome covers and thumb rests in 1982. They came installed from the factory all through the 70s.
- Steve