Noise from rear, driveshaft, or maybe bearings?

[jay'sLSV8]

So it seems that I'm one of the fellow drivers of a LS with a noisy rear. The car makes a humming, thumping type noise at high speeds (almost like the noise you hear with the back windows down). I bought an '05 LS used with 28K on the clock. It had the noise when I bought it but I figured it was something simple, tires, bent rim, alignment, wheel balance, etc. Well I had all of that replaced, new tires, new rims, and several alignments and wheel balances (darn near told me to stop coming in). I kept coming back. After all of this the mechanics decided to take a ride with me and they heard the noise but since it crops up at 75mph Ford won't touch it. I even called Michigan, no help. Now at 40K and no better, no worse.

So I replaced the easy stuff. The car doesn't make noise when I sway side to side so I'm thinking its not a bearing so maybe an out of balance driveshaft? If you guys could provide ANY words of wisdom, votes of confidence, advice, I would be a happy man. Great car but I can't get rid of that damn noise!

 

[lincoln00]

my 04 makes the noise as well... every car i have owned with a 3.50 + gear has had this howl... i think it has to do with the gear mesh... when you take your foot off the gas does it go away and come back as soon as you a ply power again??

 

[Numba1usmarine]

im having the same problem but as soon as i step back on the gas i hear that howling sound

 

[lincoln00]

its the gears mesh im almost positive... was thinking about doing a diff service... but i figure if the rear end goes out is an excuse to do the 4:10 swap..... i really could care less about a TL or LSD...