TR3a serial number

[JAMES_S_WALLACE@HP-Canada-om1.om.hp.com]

     Greetings,
     On my TR3a there are two number plates above the battery box. One's 
     brass, but the other (upper) one is painted the same as the car's 
     body.
     I looked in Piggot's "Original TR", where I saw examples with this 
     plate painted, as well as unpainted. There doesn't seem to be any 
     mention of it though.
     Does anyone know if there was a break point in the serial numbers 
     where they switched?
     I guess the real question is whether or not to leave it on the body 
     when it gets painted.
     Any help appreciated!
     Regards,
     Jim Wallace
     TS81417