WTH is this noise? Help pls...

Ok so a couple days ago my car, 2002 Mustang GT 5-speed, started making a wierd noise. At first I thought it was from the right rear of the car but since its gotten louder I am pretty sure its coming from the tranny or driveshaft area. Its was only there when I wasnt in gear before but since this afternoon its all the time. It gets quieter when I am on the gas or if I downshift(unless its just my exhaust drowning it out?). It seems to be relative to the speed im traveling and not the RPM's. In or out of gear doesnt make a difference and neither does pressing the clutch. The only thing that makes it quieter is giving it gas... Its a hard sound to describe... kind of like a wowwowoow sound... or wa wa wa like Charlie browns teacher lol. I found a vid on you tube that has the same sound. heres the link... YouTube - Mustang, tranny noise


I appreciate any help... The shop I take my car to usually closed all week for Christmas Vacation or I would already have it there.

Yeah I actually just had it at my shop because I was leaking some diff fluid but they resealed everything and top it off again with new fluid. I thought maybe the U joints but I had him take a look at it and he said everything looked fine. Can adding new LCA's upset your pinion angle and cause something like this? I just recently (like 2 or 3 weeks ago) installed new Steeda Steel lowers. I already had bbk uppers when I got my gear changed to a 4.10 and everything has been fine for about 3 months, til now.

Thanks again.

Just to update you on what it was... My differential carrier cracked in half... Not sure how? I thought that kinda stuff only happened on high horsepower cars. Im only pushing 248hp/282trq to the wheels. Nothing that I would think should crack the carrier. Any way as a result it slowly started coming apart inside and tore up all my gears and bearings and everything is going to have to be replaced. Luckily I take my car to a reputable place and since they are the ones that replaced the rearend not so long ago, I will only have to pay a little bit out of pocket and they are going to cover the rest and do all the work for free.

So I got it back today... I ended up needing new axles, gears, bearings, posi, the whole deal... I upgraded to an Auburn Posi while we were at it so I wont have to worry about this happening again and will be covered in the future once I start adding more power.