Topic: "Larger Size" Lamp Socket in Early Firebirds clusters?

[Corellian Corvette]

I'm working on a 73 Firebird Formula with original rally gague cluster.

In the upper righthand corner, there is a lamp socket that is MUCH larger than the rest of the standard lamp sockets. It's in the same spot as the fiber optic socket in my 78 and 80.

However - in the 78 and 80 the fiber optic socket is the same size as all the other ones.

Was there a different fiber optic socket in the early 70's cars? Is that socket easy to find or reproduced?

Thanks!