I got a pre-eb Sabre on the way. It's been refinshed. looks like a home job. If it sounds as good as the ones I've played, I'd like to get it professionally refinished to the orginal color.
EBMM didn't inherit the serial number database from the Leo Fender days, so it might be impossible to determine original finish via serial number. (Finish can be determined on the EBMM basses, in case you're wondering.)
You can sometimes figure out what happened by taking the bass apart and seeing if any of the original finish was left in the cavities.