There is more than one "Transition" period. Here are two of them.
The late 50s to early 60s ...
This is when WFL became Ludwig again. The badge went from WFL (duh) to a very cool blue ink badge (transition) to the keystone Ludwig we all know and love.
The late 60s to early 70s ...
This is when Ludwig went from the keystone badge to the Blue/Olive badge. The keystone was put away and the initial design B/O badge was brought out ... but it didn't have any serial numbers stamped on it yet. They decided to use the B/O badges without any serial numbers. It was a blank B/O badge. These eventually gave way to the regular B/O badge we all adore. There are differences between these.