Ya they are kinda loose there, the only upgrade is a set of bigblock lower arms as they have a sleeve belled out there and tend to be less worn. I have an nos bigblock arm and it is looser than my 40k mile originals so maybe a vendor thing. I have seen the nonbelled arms get pretty loose there, would think it could cause a phantom clunk under certain conditions. I change then to the better arms if I have them.
I think that you are ill informed. There were no "big block" suspension parts other than larger torsion bars.
