If a plate format is no longer valid, it won't be accepted into Platesmania. This is why Vietnam's gallery has the 3-digit motorcycle plate, even though some were issued when South Vietnam still existed.
Vespa motorcycle issued around 1968 in South Vietnam, still valid today: Suzuki motorcycle issued during RVN era, definitely not valid today: South Vietnamese plate under the ABC-123 series, replaced by the AB-1234 series in 1961: