A-3920779-AI Bolt, Head; 12MM X 1.75MM X 70MMOne New Aftermarket Replacement Cylinder Head Bolt for Cummins B Series Engines This M12 x 1. 75 x 70mm hex flange head cap screw is the short cylinder head bolt used on Cummins 4B, 4BT, 4BTA, 6B, 6BT, and 6BTA diesel engines. It secures the cylinder head to the engine block and is a critical fastener for maintaining proper head gasket clamping force and sealing. On a standard Cummins 6 cylinder 12 valve head, six short bolts of this size are used