Diesel Cummins Rear Freeze Plug for 1988-2002 Fit's 5.9L 2500 3500 Truck These high quality billet aluminum rear freeze plugs solve a lot of freeze plug issues. Simple bolt on application. This plug will not blow out and also has a 1/2" npt threaded hole that allows you to connect to a coolant bypass system. Bolts and O-rings are included.