When I had my Buick's body and paint redone they worked a 'putty' knife behind the name plate at the mounting posts then gave the knife a sharp hit with a hammer. To NOT scratch the aluminum use a plastic knife. To remount the name plate they used a double side tape made just for that. That tape is available at auto paint supply stores. The tape is first applied to the back of the name plate then trimmed around, then mounted on the coach. You have to get it exactly on where you want it as this tape is almost permanent.
Neil and Lynn Holman
Kirk Creek, Big Sur, Ca. coast.
1966 Trade Wind
1971 Buick Centurion convertible
1969 Oldsmobile Ninety Eight