3/4-10 ASTM A563 GRB HVY NUT HDG .020” ASTM A563 GRADE B HEAVY HEX NUT HDG ASME/ANSI B18.2.2 1987 IFI-7 AF 1.212-1.250” TH 0.710-0.758” Tapped Over Size per ASTM A 153 class C