At that mileage, there are probably a number of suspension and steering parts that, unless they have been replaced, are nearing the end of their service life. Many of the things you mentioned would not likely cause the noise you mention. I think a likely suspect would be the drive shaft center carrier bearing. The worn bearing sound comes up through the floor and could easily sound like it comes from the rear. Some on this forum have had luck quieting this bearing temporarily by working oil around the bearing seal. We had this bearing go out in a 240 and the noise just got louder and louder. Sometimes the air temperature made a difference.

I had the bearing replaced and they used the Scantech brand. That bearing did not last long so I can't recommend the brand.

The alignment will certainly cause tire wear but not that sound. I don't know what you mean by a pinion unless you are referring to the u-joints in the drive shaft.

It sounds like you need to systematically check out all the front end parts and repair what is worn, then have an alignment.