Our local Pick-Your-Part junkyards provided the easy fix. It is impossible to not find a retired Crown Vic taxi in any of the ones we visit. I paid less than 60 bucks for a used driveshaft and trailing arm, cleaned them up, and plopped them in, reusing the universal joints from the donor prop shaft. This didn’t fix my driveline problems, though. At least it didn’t cost much to find that out.