Ok, I dug into the gravel and found one where I'd parted that 58 apache, the thickness is .345. I incorrectly guessed at 1/4". They are NOT rubber (I was surprised), they are hard black plastic. There is a metal collar in the middle for the bolt to go through, that hole is roughly 1/2". I didn't measure the outer diamter of this little pad, I'd guess around 2.5". it goes UNDER the radiator support frame and the bolt goes downward through it and the bolt screws into the metal pad welded to the frame, now this is on '58, have no clue about your year. Hope that helps, lefty1
