One mate said I have noisy rattly diff - I didn't believe him, I knew the noise was coming from rear somewhere and could feel vibrations coming from rear specially on rough or bumpy roads or under gear (ie. 5th at 30kmh causes violent vibrations) sound like metal to metal knocking/worn rubber mounts (it wasn't) etc... but it turns out to be the rear diff carrier mounts shown pic below -

This is where car places like to put hoist/jack on to jack the car up, it was badly bent and was metal to metal... took me a year to find out of where it was coming from (busy with work and just forgets that I had to check out) and finally gotten to check it out - went for test drive... man it made a big difference!!!! no rattle noise or anything and I am happy to hear that...
Now, what do you tell the car places to be careful with them or what? So I saved myself $77 from the mechanic to check out...!
Cheers
AP