Originally Posted by DoubleD
All the hueblers I have seen are 5/16-18.
You seem sure it isn't, so you should either post pictures or take it to a machinist and ask him to identify it. He will use a caliper to measure the diameter and a thread gauge to measure the pitch of the threads. Should take two minutes.
you may be right, i'll need to take another look at it.
if so, i just wasted a perfectly good thread.