This is the drain plug kit we use in our Camburg 3.50 and 4.00" axle housings but can be used for many different things. You can either MIG or TIG weld the steel bung on and then thread in the zinc plated 3/4" NPT plug with a 9/16" allen wrench. The plug has thread sealant pre-applied. This is the drain plug kit we use in our Camburg 3.50 and 4.00" axle housings but can be used for many different things. You can either MIG or TIG weld the steel bung on and then thread in the zinc plated 3/4" NPT plug with a 9/16" allen wrench. The plug has thread sealant pre-applied.