Front end noise and floorboard vibration
1999 F350 4x4, TurboDiesel, 150k miles - Ok, here is the description of the problem: There is a repetitive humming/vibrating noise that I can feel in the floorboard while driving (Left/Driver's side). It would have the similar consistency to a wheel being badly out of alignment - but that wheel is fine. When I take my foot off of the gas at about 40 mph, you can definitely hear the "womp, womp, womp" sound I would say at about 5 per second. It starts at about 20 mph and I can feel it vibrate through the floorboard also. The steering wheel does not vibrate, nor does the truck pull to the left or right.
I have heard that this can be the start of the wheel bearing going bad. Is there a way to check for this? Also, any suggestions on what I might also want to start looking at?
1997 GMC C6500 Tow Beast, Cat 3116e motor, Eaton 6 speed. Not the fastest but it will pull your house off of its foundation!