Ok, maybe this will help someone that has a 350 and comes across this thread. Had my 350 for 7 years now, put over 100k on it and done all the work and modifications to it myself as an experienced home mechanic. I've had the sound describe come from all the above so I'll give a troubleshooting guide.

- Jack car up so both front tires are off the ground

- Check all plastic is in place in fenders and under engine
*had right front fender plastic come loose and tire rubbing caused vibration when only steering left

-Rotate tires by hand one at a time. Compare the 2 by listening and feeling the sping as mentioned before. As you get faster the bearing will sound almost as something is grinding or will have a catch in it (ie, it will slow down and speed up as it rotates)
*I've replaced both my front bearings. Right side at 67k and left at 103k.
*In both cases it had the grinding sound as I steered left, not right.

-Check brakes and pads. Look at rotors for heat blisters or gauges. They should be shiny and smooth if driven recently. Check brake pads for chips or damage.
*Had back left disc brake holder snap and sounded like a bad bearing but drove and braked normal

-At this point I would make sure your tires were ok and balanced. Would also have an alignment done.
*If there is also a shimmy or shake in the steering or it pulls to one side an alignment needs to be done asap or get ready to buy new tires.

Hope this helps.

 

Oh, it helped all right.