replaced my old diff with a 3.27:1 LSD from the wreckers my uncle works at - now it "hums" like mad above 80KMH and from about 60KMH there is a slight hum, part number on diff starts with 91DA, could the diff be the wrong one for my car (ED) i think he said it came from a fairlane if that helps any.

thats diff noise = its worn

try replace the diff oil with new stuff (not cheap really) but might make it quiet, else its rebuild time.

damn, i was hoping they had screwed up and had the wrong diff/trailing arms in there, back to my uncle with a "FIX IT" look on my face