I just found I need to replace both of mine: the threads are in a very poor state. I measure 1-1/2 flat to flat, and my thread gauge shows 16tpi, in a diameter of 3/4".
I think Ray at Dent has them, but I really wanted instant gratification (like delivery tomorrow!), but Amazon is no help, nor is McMaster-Carr. Any other places I should check, or should I just get some from Ray?