Even though it's not usually called out on the schematics, Gottlieb did intend for flasher bulbs (455s) to be used in certain spots on the backbox. Sometimes there's an indication on the schematic, but usually you have to go by the bulb socket. One way to tell is whether the socket is flush with the wood on the front of the insert panel. They're placed flush to better accommodate the round globe of the 455s. But this can be hard to tell sometimes.

Another quick way to tell is to look at the sockets from the backside of the panel. The sockets used for the flasher bulbs are different than the ones used for the 44s (or 47s). Note that they have a 'button' style back, whereas the sockets for the regular bulbs have an exposed spring.

The two types are shown in this picture.

Gottlieb bulb socket types

So when in doubt about whether a flasher bulb was intended or not, the bulb socket itself tells the story.

Here's what the front of the sockets look like, showing the difference between a "flush" mount for the flasher bulb, and the regular recessed socket for the normal bulbs.

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Probably a wedge base instead of bayonet? I think those are a 555.