Growl/Rumble - Not Wheel Bearing

[lincolnlocker]

I'll try to make this short. I'm trying to diagnose a growl/rumble that starts at about 20mph and is most noticable at 35-40 mph. Any faster and I don't hear or feel it. It is not the wheel bearings or the front driveshaft.

I first noticed it 200 miles after installing a rear limited slip. The logical conclusion was that something had gone bad in the install. I waited untill 500 miles and pulled the rear end apart. I removed the carrier and inspected the new bearings. Everything was smooth and tight. No damage the the bearing surfaces. I installed new rear wheel bearings after that for good measure. No change in sound.

I moved to the front. I though the sound changed slightly with steering, so I replaced the front wheel bearings. I also noticed slight play in the lower bjs so I replaced those as well. This tightened the front end and I thought I had fixed it, but within a few days I noticed the growl.

As a test, I drove down a straight wet roads locked in 4wd. The growl is much louder and comes with vibration around 20-30mph. There is a loud growl/howl under hard acceleration or deceleration.

I removed the front driveshaft. There is no noticable difference in sounds. This should eliminate the ds and tcase as suspects.

At this point I do not want to spend any more money without a firm diagnosis. My gut tells me front carrier bearings, but that seems to be a really rare event from all my searching. My truck only has 50k miles on the clock.

No play in front pinion flange. The front gear oil looks clear, but there is no magnet on the fill plug to catch filings.

Any thoughts?

2001 Focus Zetec 165 000 km 5 spd. Winter tires (on since Dec. 07, second season). I began to notice a growling noise that picked up with vehicle speed, starting around 30-40 km/h. The noise is less pronouced on left turns and much greater on tight right turns at speed. Seems to come from drivers side, possibly front, but difficult to pin-point. Jacking up the car and spinning tires reveals no noise, and pulling on all 4 tires reveals no play.

I'm stumped. Not sure if it's related, but the left side tires seem to be wearing excessively on the outside. Camber "looks" fine, I checked it a year ago and it was within specs. Unlikely it changed as there were no accidents, and suspension components seem intact. Sometimes get some vibration when braking, intermittent, replaced rotors and pads last summer, still in good shape. REcently rotated wheels, all tight against hub.

Ideas? It might just be the tires on the left side. I need to switch back soon to my all season tires, but since it keeps snowing out here I'm waiting.