I would suggest a Tridon SD12 electro-mechanical flasher. They're a little more pricey that regular electronic flashers, but extremely reliable, I've been running them in both of my trucks (front and rear LEDs in the '55, front LEDs in the '85) for several years with no problems at all. They also make an audible click when they are on, just like the old style thermal flashers do. Any parts store should have them on hand, especially if they deal in HD truck parts.
BTW, the Tridon flasher is USA made, unlike most aftermarket electronics these days.

Last edited by LONGBOX55; 03/03/2016 10:31 PM.
Bill Burmeister