Funny you bring those up. I have a story about them. Went to high school with a guy one year ahead of me. I had already been working on cars about 8 years when we met. lol
Anyway, he had a 69 Cougar XR7, factory 351W, 4 barrel, 4 speed. Midnight blue metallic and cragar five spokes. REAL cool ride.
One day I saw him turn in to school. All the lights on that side flashed. We had a science class together, so I told him that his turn signals didn't work right. He had no idea how they were supposed to work.
So, he brought it down to the auto shop during my period and I fixed them. Someone had bypassed the control box to install a trailer connector. We 86ed that and I wired it all back like it was supposed to be. He couldn't believe it and we stayed good friends until he graduated and moved away.