Harness question

[z28rob18]

Didn't know where this goes but. I'm working on installing the 5pt harnesses and was gonna put bolts for the lap belts in the factory bolt holes. I don't have the old bolts where I am. What size bolt is it anyone know? And course or fine?

[96LT1355Z28]

Course thread, I don't remember the thread size but I know the hex head is 3/4".