At some point you'll have to determine how to pass the window switch wiring from the doors to the body. Some original door shells have dimples that indicate where to drill for the original wiring used for courtesy lights or speakers, but this fastback had reproduction door shells. In a nutshell, we looked at the cowl panel and door shell and picked a spot we knew would have no interference. The cowl panel is easily drilled from the passenger compartment. The included grommets in the kit take a -inch hole.