the led tails are stop/turn/tail. The cruiser has a separate wire for each side turn signal but the tails and stops are wired tgether. Make sure that you are noy connecting the 2 turns together ANYWHERE. Also you may be rying to wire 2 lights per side as you did not say. If so, you must wire one for turn tail and the other for stop/tail. If you do both for stop turn and tail then when the turn signal flashes, they both will flash. when you hit the brakes they both will brake. There is no way to wire them to both light for brake but only one for turn
also forgot this, the stop lights are wired into a single circuit (they both come from the same source) and so do the tails. On standard stop/turn/tail led lights, there are 3 wires. one is the ground, the other is the tail, the third is either the stop or the turn. By wiring the third in as both the stop and the turn, the stop light circuit is acting like a bridge for the power to flow to the other side light because the electricity doesn;t care which way it flows in the wire.
Try using one of those walmart converters. They are for vechiles that have a seperate turn and brake set up. The converter is made by hoppy. Try that and let me know how you make out. I have a 74 that I'm going to put leds on, and want to make sure it works. Later