4BT3.9 Cummins Cylinder Head 3966448 Parts Catalog Ref No. Part Name Part No. Required 1 Pipe Plug 4931643 2 2 Pipe Plug 3906619 2 3 Hexagon Flange Head Cap Screw 3920779 4 4 Hexagon Flange Head Cap Screw 3920780 10 　 Cylinder Head 3967460 1 　 Intake Valve 3802355 4 5 Valve Collet 3900250 2 6 Intake Valve 3920867 1 …