Steering Column Rattle/Clunking Over Small Cracks In the Road

This problem has taken me FOREVER to investigate the source.

I hear this very faint clunking/dull rattle coming from the dash (and also felt in the steering wheel) when I go over small cracks/small bumps in the road. However, I don't hear anything over larger bumps or cracks. I checked everything I could in the suspension components and everything looks good. Bushings are all looking great.

I was on a road trip up in Vermont this weekend and found myself on a dirt road with plenty of small ridges in the road and the clunk was almost constant. What a perfect opportunity to investigate the source of the problem I thought! What I noticed was that when I held onto the steering wheel very loosely, the clunking got significantly worse. When I grabbed onto the steering wheel tightly and put upward or downward pressure on the wheel, the clunking stopped completely! I played around with this theory for a few miles on the road and everything checked out.

What could this possibly be??

 

I thought about the steering rack being loose but I would expect there to be slop in the steering wheel when turning (this happened to me in my old GTI). Unless the rack is somehow pinned but not tightly fastened down?

Anyone familiar with how the steering rack bolts to the (I'm guessing) subframe?