Rickenbacker 4003 serial Numbers on newer models.
 

Are there additional serial #'s on the newer 4003's beside what is on the Output Jack Plate?

Don't know what you mean by "additional," but often (perhaps usually now) the serial is repeated on the unpainted wood inside the control cavity in ink (marker). Can't say that is always the case, and it is sometimes possible that the serials may be different. Since the instruments are hand assembled, inconsistency is a possibility. Also, one that is slated to get a certain number may be pulled off the line for a correction and be separated in the sequence and receive a later serial number.

Thanks, I was mostly just curious. It seems like a serial number shouldn't be so easily removed or replaced.

No different than the thousands of Fenders with the S/N on the neck plate.