300GE whine when slowing down

[luky]

Hi guys,

I would like to ask You for a help with my 1991 300GE auto (463.228, M103 engine & 722.3 gearbox, fulltime 4x4). The car has original 160.000 kms, I bought it from the first owner with full service records, but it wasn´t used very much for about last 3 years as the owner has many other cars.

My problem is a silent whine I can hear for several seconds after I release the throttle pedal when slowing down. Can anybody give me an advice what can be the reason?

The car has new fluids in the diffs, t-case, gearbox and new engine oil, new front and rear brakes (nothing caused any change).

There are still a few issues I ahve to fix, which may be related- the exhaust joints in front and behind the cat convertor seem leaky, the engine has some vaccum leak, which causes a bit rough idle and the front tires are newer than the rear ones and have about 3 mm more tread (less than 1% difference in total diameter, can this cause some considerable t-case stress?).

Thank You in advance for any thoughts,