I purchased a great 05 Road king last summer and the guy I purchased it from gave me headlamp & directional lamp fairings. I tried installing them annd when I put them on they were able to spin, someone suggested a dab of silicone to hold them in place. Is that the solution?

 

When you say "fairings" do you visor .... like an eyebrow for the headlight and turn signals ? If they are visors then there is a rubber filler strip that helps keep the headlight visor prpoerly mounted. I haven't seen this problem on the turn signal visors. I have had them on both my 1992 and 2009 FLHTCU with no problems. I love the "Old School" look. Hope this helps.
P.S. Silicone could work and a small dab wouldn't hurt anything.