Not exactly what you asked but I put seat belts into my 1941 Ford. I planned to as soon as I got it, but I dragged my feet a little. One day after working on my car for a bit, I took it for a short test drive and as I pulled out of my alley and turned left the passenger side door popped open. I hadn't shut it properly. The door latches on these cars are crap compared to a modern bear claw latch. Not complaining, that's just a fact. Things have improved a lot in the past 82 years.
No damage to the car. My 50 year-old screw driver rolled out and got some new scratches. Obviously no big deal. Of course, there are so many ways it could have been serious rather than just embarrassing.
I quickly ordered some color samples from Juliano's and ordered set of shoulder belts with lift-latch buckles. To my mind, they're barely noticeable, blend right in, and don't look out of place in my '41 but I feel an order of magnitude safer.
By the way, for maximum safety, you want the third point as high as possible on the b-pillar. I won't go into it here but ask me if you're interested why.
