Amsoil BP40 Fitting, Self-tapping hollow bolt.
Doesn't look like NPT (too aggressive) but it's a self-tapping hollow fitting, pretty self-explanatory.
What does it connect to? That will be your inside thread.
An NPT fitting would probably work fine for the "self-tapping" replacement (drill an appropriate sized hole and in she goes). So whatever female thread to NPT adapter should be perfect.
You could be a little more verbose; as we would say to our excited children "Use your words". Why should I have to Google "Amsoil BP40" when you KNEW it was a fitting for the Amsoil bypass system and just didn't want to tell us? That kind of post doesn't often get replies, just sayin'
Did you try asking Amsoil, or do you think it's a State Secret they won't divulge?