I'm sure this has been discussed before, but i'm not to successful with my search. I noticed with my turn signals for my 71 had different bolt spacing for the mounting studs and one lens is longer then the other. So what year corresponds to what lens. One of my turn signal fits airdam perfectly(bolt spacing), the other side is more narrow on the spacing. I'd love to have a matching set, but not sure what year to get for the wider spacing.

I'm not aware of any differences in the 240 and early 260 (North Am. market) turn signals. The urethane air dams that I have seen that are meant to accept the 240 signal lenses usually don't come drilled for the mounting bolts, meaning that the owner had to do that, which leads to inconsistency. Perhaps this is what you are seeing?? Love to see a picture and some measurements of the turn signal housing themselves to see if there really are differences. You never know.