ive got some noise in my diff as well and I was going to try moreys in it as its very thick but ill try the m/disulphide in it so where do you buy it/is it a grease or just a oil?
Don't go for thick, it draws energy resulting in fuel increases that add up over the miles and years.
This a one liter bottle I bought from Blackwoods, long ago.
It was a small amount of this, added to an oil change that just shut my Diff up.
I have used this extensively on heavy plant and equip in the mining industry etc, in the day, to keep worn out gearboxes, diffs etc alive and extend duty cycles until the components for tear-down were in.
I serviced auto for a while, one customer had a howling 173 HQ s/w diff from towing a caravan around Oz three times(seasonal employment).
I put three 60Gram tubes in that, it only took three weeks to quieten.
I have built/optimised 72degree V6 Cosworth/Mercury formula outboards. They download RPM peaks of up to 14,500 when free air prop-walking(incredible engines, near to indestructible when balanced and then "Harmonised" correctly), I always added it to their right angle drive gearcases, I still do, even to my smaller outboards.
http://www.itwpf.com.au/molybond_lubricants/product.aspx?productid=69http://www.blackwoods.com.au/part/05182474/oil-supplement-molybond-formula-25-60gm