Is the original bolt a flanged head bolt or standard hex head grade 8?

GM#3914816.
It's a "Hex Flange" 1/2-13 x 3.0" 3/4AF Grade 5.
www.amkproducts.com #B-10079, $12 buys the pair.:thumbsup:

I dug up some originals I have, and they are flanged like Steve said.

Thanks. I bought some but you never know for sure. Some of the repro sources are buying them from AMK.

..and some aren't.
I bought the 2 screws (advertised as "correct" through Classic) that mount the center vent in the dash of a '69 and they are Torx heads.. Can you believe it?
I don't think the Torx design even existed back then, let alone me go out and buy the tool to install the damn things.

I also got a PS bracket with a bolt in it that was 3/8"unc and a 15mm hex. No grade markings either. Obviously Chinese rubbish.
I hammered the threads and bin-ed it. Not on my car pal! :noway: