Well, I just finished fabricating a 1 in TC drop and... so far so good. I took her out for a test drive after the rain stopped here and there was almost no vibration and the noise is gone. No more grinding noise.
I will have to confirm this once the roads are dry but I'm remaining cautiously optimistic. Thanks for the suggestions, next to electrical bugs these stupid noises are the hardest thing for me to track down.
Yep, roads were dry today and the noise is gone as well as most of the vibrations!