The plug is 1/8 pipe. The bung I guess was about 3/4 inch diameter slug of aluminum bar stock. I never went to a machine shop, just a welding shop with a tig welder. I just hand fitted the slug to the case with files and a dremel etc. after welding I draw filed the welds to blend with the pan rail bottom and sides. The red rill you new access hole and tap with 1/8-27 pipe. Just time and work mostly. You probably don,t need this but just take your time and be careful. You don,t want to trash the case. Aluminum is soft and easy to work with.
