Thanks for replying. Stanton, the original nipple was rusted in and destroyed when removed leaving the threaded portion in the hole. It was beyond removel with and easy-out so I drilled it out. The hole size is right for the threads of the nipple I have, purchased many years ago, so I'd like to use them.

Kutter, Thanks for doing that research for me, very kind. I would not have thought to look at Track of the Wolf for what I need. I think I can use the 1x6 tap.

Thank you both for the help!