Rumble When Braking 1990 300ce

[Markus]

So braking from highway speeds to about 45mph car rumbles under braking, appears to be coming from the front. New rotors, pads, and rebuilt all 4 calipers 2 years ago, last year new front lower control arms. No shudder or rumble at lower speeds that would indicate warped rotor. From high speed the harder I brake the louder the rumble.
Suspecting front wheel bearings? All quiet coasting, or going around corners.
Thoughts?