See https://www.hdforums.com/forum/touri...k-rattled.html for the first part of this saga...

Well, I went chasing a better solution, and I think I found it! I made oversized rear bushings from aluminum, and made front ones from a plastic bushing material by the name of Delrin. Delrin is used to replace bronze bushings in industrial settings, so I gave it a shot. I was pulling the tourpac anyway to add a George Anderson relocater, so it was simple to take the rack to the lathe and make TIGHT bushings.

They've been on the bike and have about 300 miles on them. The aluminum fronts developed rattle and slop in the first 100 miles. The Delrin ones have a tiny bit of play, and no rattle. Short of hard-mounting the rack, I think this is about as good as it'll get. When the rears show wear, I'll turn some Delrin ones for those, too.