You can find 2-prong style flashers for LEDs on internet, I sourced one for a friend last year (I don't remember the supplier though, just search for '2-prong led flasher'). My friend ended up reinstalling the incandescent lightbulbs though (not enough power on the stop lights).

On your other post, you also mention going HIDs for the headlamps. I just have one thing to say to that : Don't use H4 HIDs!
H4 lamps are dual-filament, HIDs are not. Some attempt to duplicate the H4 low/high beam function with a moving collar around the bulb, or by moving the bulb itself in a bushing.
Better use H1s or H7s since you have a 4-light system (or better yet, good wiring, relays, and good-quality halogen H4s, 55W for low/high on the exterior lenses, and 85 to 100W on the high-beam only interior lens if you need that). Way better than aftermarket HIDs in my opinion.