I had similar problems with my MkI 2.7TD, when slowing down through the gears, I had this whine...
I used molyslip in March 2007, this is what I wrote on a previous thread.
I have now changed the gearbox oil, added 105ml of molyslip G and 100ml of multiglide, I jacked up the passenger side and overfilled by approx 200ml, I took her for a 20 mile drive to get the oil circulating, and 2 days later the gear box noise has reduced by 80% I could not believe it.
I did the transfer box, but only added 50ml of G and 50ml of multiglide.
Tip, in order to fill the gearbox and avoid gear oil running down your arm, get a 1 metre length of garden hose with a funnel at one end open the bonnet and thread the hose down the back of the engine, ty-wrap the funnel to the fuel filter hoses then go below and position the pipe into the fill hole, but wedge it up so that the pipe flows down into the gearbox, otherwise the oil will run back along the hose.
Warm the oil container first (in a bucket of hot water) and it goes in a treat.
Worth a try, still drives well, no major noise now, there is still some whine but it's probably ok for another 2 years I guess..
Hope this helps.
Best regards, Rustic
