RE: Late Model Headrest Attach Screw Size?

["Matt Jacquet" <matt@vander-bend.com>]

Just did this one!!

It's an M6 thread; the head would be optional but I use a flathead phillips
drive. Length is dependent on how you mount the rest. I mounted mine using a
flat then a finishing stainless washer from the outside of the vinyl, as I
have no brass grommets installed. came out pretty nice. I needed a 20mm
length screw to make this happen. If you have access holes then a 12mm screw
will work.

What's the sizing on the screws used to fix/attach headrests on the
'68-70 cars?