Looks like the right part to me. I would advise against using hardware store bolts for this application. The "bolts" are actually more of a stud, and require the splined part to lock them into place. They are also 1/2"-20 fine thread. I agree with new nuts and lock washers, but do not put locktight on them, that's overkill, and might upset the alignment mechanic when he goes to set camber/caster.
