I want to put spot lights on my '60 Buick LeSabre but have no idea on what is involved. I haven't got the lights yet because I don't know what size I need, I went on the unity web site and they have a application finder that says I need one with 12 5/8" shaft and 17 1/2" center to center. Can anybody fill me in on how to do this. Also I don't want dummy lights