On my new-to-me 1987 300TD the car makes very audible hum/growl when the steering is even slightly to the right, i.e. even when going straight if the wheel is a tick to the right of 12:00 the noise is audible.

It sounds like it is coming from the front right but it is hard to be sure.

When I first got into the car I assumed it was wheel bearing issue, however I replaced the inner and outer wheel bearing on both front hubs when doing the brakes recently without any discernable effect on the noise.

Any tips on what I should troubleshoot next?