For LED bulbs and blinker issues they can now be had with a resistor in the bulb base. Much better choice then wiring in resistors (ugly) to give a load to the blinker controller (Anti hyper flash). I used these types of bulbs on my motorcycle for a clean install. You'll pay more but it's a plug and play.
I also found on my M998 with originally incandescent bulbs I could run reg very bright 12v/24v LEDs in the rear of the truck and the blinkers worked fine but not when I tried to add in LEDs to the front lights.
Mark
Mark
That's where I'm at now. I put TruckLite taillights in and the signals flashed fine, but after I put the TruckLite front turn signal assemblies in, they worked properly with the light switch in STOP LIGHT, but
did not flash with the switch in SER DRIVE
. I read a work-around somewhere - take the bulb out of the turn signal lever in the cab, and when that bulb is out they flash normally in all switch positions.
So that's how I'm running now - no green light in the signal lever.