Only the bolt should be different when used with the newer spindles. The ball joint is actually unchanged.
Very early cars such as 83 and older had a smaller diameter ball joint post IIRC.
There are basically 2 different ball joint families for the 85+ cars: Cast control arm ball joints, Stamped control arm ball joints. The only real difference is that the snap ring groove is lower on one (I think the cast arm version).
Strangely I am pretty sure the Neon also used the same 2 ball joints....
This includes the Neon and SRT4 aswell where the cast arm neon ball joints are the same as the 91+ cast arm ball joints and the stamped arm SRT4 ball joint should be the same as our earlier stamped arms.
I do still have Hawk pads for the 91+ front brake setup!
-Rich