I'm running HD spots & signals on a Yamaha bar.
HD lights have captive hardware that is NOT metric and will NOT thread onto your Yamaha signals.
Keep that in mind if you're shopping and looking to mix & match parts from different makers.
I got my whole HD lightbar setup for $75 on CL along with 2 boxes of extra parts, all long ago sold separately.
I just searched for Harley Parts on CL and found them. Lots of guys yank the whole light setup off HDs.
The lights are shown in my profile pic, but here's a closeup shot.