Unfortunately, for the Pre-EB Sabres (as opposed to the 'Rays), the serials don't really give any indication of age. The neck and body will be dated but you have to have the neck removed to see them.
As a broard indication of age, Sabres with toggle switches on the control plate (and pickups with exposed pole pieces) went from 1978 to c. 1983. After that a lever switch and soapbar pickups were used.