I just did a whole pile of them, and used grade 8, 1/2" bolts. I threaded the hub. I'm going to use Loc***e on final ***embly.
I don't have the number, but it was a later Jeep Cherokee stud and was a MAJOR pain in the a** to figure out. Watch the spline location, most I found easily did not have the splines in the right place to lock the hub. By the way that was for hubs outside the drums. There are two different approaches to this.... hubs outside the drum and drums outside the hub. Good luck with it!
I use Dorman 610-234. These are readily available at any decent parts house. I know some guys drill the hubs to take these 1/2-20 studs. I just ream the holes to .6003 with a chucking reamer and press them in.