drain plug for 8 3/4 housing
got a reply from Doctor Diff. He didn't have any on hand so he sent me this link:
https://www.amazon.com/dp/B07QYGMVT5/?tag=fabo03-20 I ordered one. Since the bung is welded on the outside of the housing there is little or no protrusion into the housing so no worries about getting too close to anything.
Thank You to Cass for his help!