Altec speaker identification ?? 604-G and 604-H ???

I am trying to tell how you can tell one Altec 604 from another Altec speaker when they are unmarked..............Does anyone have any first hand information about that..........I can't call Great Plains Altec about  that because they moved to Mexico and we I called them, nobody could speak English, so I couldn't ask any questions........Your Right ??   Another American company move south.......