What are we solving for? Looks like folks have the solution no?
Whatever the case, I suspect the capacitors would be the thing doing the "flashing". Not sure why nobody's been messing with hose. I'm not familiar with flasher circuits so maybe that's a bad suggestion, but most basic analog (non-digital chip timer circuit) oscillators use capacitor networks for speed. The "astable mutivibrator" is my favorite oscillator circuit ... based purely on the name of course.
On second thought, what would be nice is to replicate the flasher base so that any $2 eBay junk Chinese flasher guts could be scabbed onto a base that plugs right into the OEM socket.
Anyway, you called me??