Sun Visor Mounting Bracket Hardware

[GMCPaul]

Getting screws done for the Blazer /Jimmy sun visor mounting bracket to windshield frame and from sun visor mounting bracket to top. We want to make sure to get this right so looking for feedback

4- Sun visor Phillips Head Screws = 5/16-18 X ? with .50 diameter head
So for above we need the measurement from top beveled edge of screw head to threaded end?

Everyone posts the screw is 3/4" long, so what we need to know is the 3/4" everyone is referring to the threaded length? Because then actual screw length = 1", if the threaded length is 9/16" then the screws are 3/4" length.
The manufacturers go from bevel edge to thread end and we suspect everyone is posting the threaded length.

We also assume most would prefer the sin visor brackets to top screws be included in kit. Whats everyone's opinion on this or should it be in the top mounting kit we'll be putting together?

Then we see a lot of posting about the sun visor bracket to top fastener being a hex bolt but our research shows it was a 2 1/2" long 5/16"-18 Phillips head machine screw. So can anyone else confirm this real world?? If so could you measure the head diameter so we get the correct width head?
We will be doing all of these in stainless steel.
We’ll also be putting together the removable top mounting kit and may need a little clarification on a few items in it which I’ll post separate about.
Paul Jr @ GMCPauls