Rear view mirror location

[GTP091]

I need to remount my rear view mirror. Not entirely sure of the buttons location on the windshield. I’ve taped the halfway point for center to center but not sure how far down it should go. 5†looks about right. Can someone measure the distance.from the top of the mirror mount button to the headliner for me? And verify the mirror is centred on the windshield. I’d be enternally grateful.

 

This would be for any 91-93 Grand Prix.