Hood/fender mounted turn signals - Installing?

Hi, I know there are the sort of "308.cal" Projectile on a fin base shaped ones, and the sort of trapeziod/cube shaped ones that are more square, Has anyone installed these on one that didnt already have them, or are there terminals in the harness/wiring/fuseblock /flasher and sort of cut out provisions or a pattern for the mounting on the fenders? And where to find them?