Plain Plug Gauge for ID in Pre Drilled Arm Go 13.2 to 13.203 Cyl. 0.0001 Len. 50 to 51 NOGO 13.248 to 13.250 Cyl. 0.0001 Len. 10 to 11 / Std. Gauging area should have lapped finish. Gauge No. PPG 13200.13250