Metric fasteners will generally be identified by markings on the bolt head and nut face The following figure displays the different types of identification that will be found on GM vehicles Most metric fasteners will be identified There are however some exceptions MANUFACTURES Numeen nsenasems eorsr srnsueru iosnrnmcrion r I iso M I l I V 3 V I 9 8 I i if I L I Mermc BOLT IDENTIFICATION NUT STRENGTH me usixcs univ rnsmrricmoiv I I I I O Oil o 0 I I I L 4 T METRIC Nur IDENTIFICATION I Common metric fastener strength property classes are 9 8 and 10 9 with the class identification embossed on the head of each bolt Customary inch strength classes range from grade 2 to 8 with line identification embossed on each bolt head Markings correspond to two lines less then the actual grade i e grade 7 bolt will exhibit 5 embossed lines on the bolt head Some metric nuts will be marked with single digit strength identification numbers on the nut face The following figure illustrates the different strength markings N N W W W a q R gw w w cams z cams s emacs 1 emma s GM 200 Mi GM zao M GM 290 M1 GM enc M Customary inch bolts Identification marks correspond to bolt strength Increasing numbers represent increasing strength r N N N N N N Q Q Q q r q I r Q1 1 its Q1 1 Metric Bolts Identification class numbers correspond to belt V V 4 strength Increasing numbers represent increasing strength GM PARTS DIVISION OENERAL MOTORS CORPOFIAT ON CHEVROLET 10 M z REV 9 18