lazyxj, you are correct, the Clayton bolt will only fit a Clayton HD Track Bar.
I found these part numbers on another post,
Bolt is 6505 549AA (I think it's just a 10x1.5)
Nut is 6506 264AA. It sits in a small recessed area so you can't get a wrench or socket on it.
I ordered both parts from my local Jeep dealer. $13.95 for the nut and $2.95 for the bolt.
The Grade 8 nut at the hardware store was too big across the faces to get a wrench on it once in the mounting bracket. The grade 8 nut for a 3/8 fit in the bracket better and I could get a wrench on it but the bolt was just a little smaller which led to a small amount of movement in the Track Bar which I do not like so I ordered the Dealer parts.