They are a special bolt, the shoulder fits the inside of the gear, threads are 5/16-18... Guess that with this you could fake them, MY (vague) recolection is that they are about 5/8" under head... Lots of guys will have spares of these, I would donate four- I'm not home right now- I will, if someone closer (I'm near SF, Ca) -doesn't do it first.
Karl