How to drill and tap a Muncie M20/M21/M22 case to accept a 1/2" drain plug.
Drill and Tap:
www.amazon.com/gp/product/B01MG92FX1/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
Drain Plug:
www.amazon.com/gp/product/B002A33SUE/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1