The Volkswagen T1 Bus emergency flasher system was available in 1966.
Volkswagen mounted a nice illuminated hazard warning switch in the USA T1 Bus only. The switch had the same design like the wiper or headlight switch. The knob of the emergency flasher switch was red with the inscription “VW EMERGENCY 88”.
If you want the very best for your T1 Bus dashboard, then I recommend that you mount the 1966 VW EMERGENCY 88 flasher switch as you can see at the first picture. I saw that nice T1 at great Maikäfertreffen 2012 in Germany.