Main mod is to mill the base so you can just plop it in the mill vise. Since I have a BP 5" that means removing some material so that it will fit. Right now I need to remove the jaws for it to fit.
Another mod is to put clamping slots so that you just need to run studs up and nuts.. Rather than run clamps to it.
My mod was to mark the front collar to indicate where the alignment dowel is for the 5cs, so I am not fumbling for it. For me a very valuable time saver, and frustration saver.
@Cadillac, I always thought air spindle was so that it just rides on a cushion of air, that the tolerances where so perfect that the trapped air was what it rode on.. I didn't think it needed air added. I watched Dan Gelbart
https://www.youtube.com/user/dgelbart/videos make one. It was from precision fitting, and the spindle just floated on air, I realized I will never be that good.. I would like to be, but it won't happen. Too many years to get there, and I am on the decline, not on the upside.