Sami asks whether or not the 66 double cab had the flasher installed
later (the one for the headlight)....NOPE...it was original equipment.
Prior to 1966 the headlight dimmerswitch was on the floor in Typ2s...

There is no difference between flasher relays and dimmer w/o flasher
relays...it is just a matter of which wires are connected to the
flasher switch.

Ric