6 bolts were the correct diameter but 0.1 inch too short, while 84 bolts were of the wrong diameter (0.026 undersize).
Kaylock floating anchor nuts are attached to the airframe and are elliptical in shape prior to insertion of the bolt. The nut shape permitted sufficient grip for the reduced diameter bolts to be torqued to the correct value, but insufficient grip to retain the bolts against pressurisation forces.