Anyone know what this diff noise might be? (video)

[prelude48]

Here is my diff at 100kmhr on jack stands.....what might this noise be?
[youtube]http://www.youtube.com/watch?v=MfNVVY5c79c[/youtube]

[Towncivilian]

Are you sure that noise is not emanating from the driveshaft? How old is the current gear lube in the diff, and is it at the correct level (remove the fill plug, stick your finger in - you should feel fluid)? LSD or open diff?

[prelude48]

well when im laying under the truck listening around, i heard it from the driveshaft, but thought it was something else because there is nothing that would make noise. so as i got closer to the rear it got a little louder and then i put my ear to the back and could hear it clearly. new fluid, its lsd and yes its at the proper level.

Think is something else?

[Towncivilian]

What fluid did you put in? Was the noise present before you did the change?

[prelude48]

80-90w and yes it was... i have a vibration off the line until 30km/hr and only under heavy acceleration. check out my other post if you dont mind...."if you changed your trailing arms?" i determined it was the rear diff because i mounted a camera on the diff and it started to shake at the time it normally does.

[ARKQX33V6]

When driving the rear wheels did both rear wheels turn...the same direction when starting off? Raise rear and in N hand turn 1 side and see if other turns that same way, try other side.

I hear a bearing on left side but camera work is hard to conceptualize.

If you hear noise in rear end, the most likely is the main central bearing at the drive shaft input.

Drain the rear end, let sit empty.

Try rotating the drive shaft by hand feeling for resistance, you may need to disconnect from transmission.

Remove diff inspection plate, then look at insides while turning without fluid.

Your video demonstrates a bearing noise, but I can't tell from where it is at because rotational speeds are too high and there is more noise than just the diff