U-joint?
30 spline/7260 joint sounds right.yokes can be had from brewers/passon and the bag.
Been doing service and restorations on primarily British cars, but lots of American iron for nearly 50years.
I would say, between 20-30 percent of the U-Joint cups on British cars spin quite happily in the yokes, have seen it on a few NA cars as well, have never seen it cause a problem. Once loose and spinning, they don't seem to cause any undue wear on the yokes. I even oil them occasionally, and, just let them spin.
Does make changing them much easier if they are a nice loose (but, not sloppy) hand push fit...
If you are really concerned, spray them up real good with brake clean to get rid of oil or grease, and, hit them up with some good wicking Loctite.
As others have said, DO NOT WELD THEM.........