Topic: Age of AKG SE 300 B body determined by switch color?

[JLMoore3rd]

I picked up a pair of AKG SE 300 B bodies a month or so ago & they both had white roll-off switches... Then I picked up an SE 300 B + CK91 cardioid capsule combo (C391B) and that body has a red roll-off switch. Since there aren't any serial numbers how would I tell the ages?