Hi H
I bought a bag of 100 of actual clutch head screws which work in most places in the cab, like door panels, trim, etc.
I think I got them here:
https://www.classychevusa.com/index...084/category_id=35/mode=prod/prd1084.htmThese are the right size and thread pitch.
The floor boards require different hardware, 1/4-20 machine screws if I remember right.
They were originally the tapered head/counter sunk type of screw, but the holes in the floor boards are often worn too big for the original style to work.
So I used pan head style with small flat washers for the floor.
They are covered by the floor mat anyway.
What you use here will of course depend on what you replace your floor board with, but you will be screwing into 1/4-20 threads.
Hope that helps.