This set of 4.3mm Ti64 Titanium ball studs use the correct vintage 4-40 treads and are made in the USA!  These are designed for the Grand Prix 3D '91 Worlds Prototype Conversion Kit

Kit includes 17 ball studs for builder flexibility.  Generic picture used for reference only.
 
Now available with either a hex our round collar.  If hex collar is selected the 0.1875" stud will be substituted for 0.2" studs.