If you replace both front & the rears with leds, you'd need an *metric diode kit* to reconfigure the idiot light wiring. Otherwise you'd get cross-feed (4-way flashing). If only the front but not the rears, or visa versa, you might not need an electronic flasher. As a temporary fix, just pull the idiot light bulb for the turn signal.

I had to have both a diode kit and a Led flasher installed on the Tourer to get everything working right. It was not necessary on the Interstate, just a LED flasher.