I have a loaded Fender pickguard from a used Strat that I bought years ago. There are hand written numbers on the back of each pickup. They read 78708 (B), 78701 (M) and 78704 (N). Any idea what pickups these might be? I know that they came from an American Strat, but it was used, so I don't know if these were the original pickups or not. In any case... and help would be greatly appreciated! Thanks!