Thank you for all of the years of information added to this site, and replies to questions. I know on Facebook, one can get instant gratification, replies, and heckling, but way too many questions asked the same way, for me to go there, so here I stay.
Sometimes you just have to hunt out a small Mom and Pops Hardware Store to get what you want. Sure Home Depot and Lowes have a lot of things, but there is no service service like the small Hardware Store. From asking a few here about a plug for my M1 coolant passages, I was directed the Hardware Store. These places are being replaced by the Big Box Stores, and online purchases, but when you need something that is not so ordinary, they come through again and again. Sure, Home Depot had the NPT Thread Plugs I was looking for, but did not have the NPT Tap. They said I had to order it online. Looked for an older employee with a really old apron, but didn't see one. I stopped while inside the "Big Box", searched for a local Hardware Store from my phone, and saw they had what I needed in stock. Only 7 miles from my house. Called them to verify they had it in stock, and made the trip there (love the original creaking wood floors in there). Drill bit, and NPT Tap was in my hand for about $11.00 and off I went.
Bottom line; support your local Hardware Store, and this site, but please use the search function here and go back many years before asking.