kaaz 2 way humming noise?

[mrmarbles]

I recently swapped in a kaaz 2 way LSD. It was already assembled, I bought it used from someone on a different forum. I had a shop put the LSD into my stock pumpkin, used the axle flanges from the pumpkin it came in from a 180sx, (they were the same exact size just different spline count and 5 bolt), and used axles from a j30. I filled it up with GL-5 conventional 80w/90.

In a straight line, the rear end makes a humming noise that increases in pitch as I speed up.

Everything is bolted up correctly from what I can tell.

I don't think the noise is normal... Could it be that the backlash is set wrong? Could it be the wrong gear oil?..
Any help is appreciated.