I beg to differ. The 3/8x10 & 3/8x11 are currently very common pins, nothing at all 'odd' about them.
Also, you don't bore out the 10 and it automatically becomes an 11. They're two different pins (tpi).
So which do you want, a 10 or an 11? Seyberts offers both.
If you have a 10 and want it converted to an 11, they can do that also (and visa-versa).
Seyberts: 1.877.314.2837. Ask for Rick, he's very knowledgeable.
Just trying to help.
KJ