My take? Airheads are all about "Simpli Fi". For decades I've used a $5.45 Buss flasher relay that does everything that the stock OEM /5 unit does. Even works with LED lamps. I'm sure that there is a 3 or 4 prong Buss repaly that will work.
'73 R60/5 Toaster
Luddite. Not just a philosophy, a way of life...