When I got my 66 Charger back in 2010, car had worn fuel pump push rod issues resulting unpredictable stall outs while driving, which left me roadside a few times. I decided that 4 way flashers would be a necessary addition. I came up with my own design and modification that is minimally invasive to the cars electrical wiring, only costs about $ 25 bucks and a few hours time, and uses readily available parts from an auto supply store. If anybody is interested, I'll be glad to post the written description, pictures and schematics..