The correct bolts should have been 10-32, but the replacement bolts fitted were 8-32.
From the report linked to above:
“The bolts engage with 10 UNF Kaylock floating anchor nuts mounted on the inside of the windscreen frame. The replacement windscreen had been installed with 84 bolts (A211-8C) whose diameters were approximately 0.026 of an inch below the diameters of the specified bolts but of the same thread pitch, and six bolts (A211-7D) which were of the correct diameter, but 0.1 of an inch too short.”
The incorrect bolts were “only” 0.26 of an inch smaller diameter than the correct bolts. Probably if the appropriate engineer were doing the task he would have noticed the difference, on the other hand a manager, not doing his usual job but trying to get an aircraft ready for service didn’t.
Incidentally, it is common for windscreen mounting bolts to be fitted from outside the aircraft, but usually the screen is positioned in the aperture from the inside the cockpit against the frame. The bolts go through the frame then through the screen and are secured by the locking nuts. This means that cabin pressure will keep the screen firmly in place. The bolts are obviously then not so critical.