Quattro Clunking Noise

Can anyone help ?

I have a clunking noise when I let the clutch up an engage the drive. It is only really noticeable in first when I am starting to move off from stationary. It also does it when I press the clutch pedal on stopping. I can minimise it by being ultra smooth on the clutch pedal but it is usually there.

I have had the car up on a ramp with a mechanic and we managed to isolate it to the prop shaft ( the main shaft from the front diff to the rear). There seems to be to be quite a bit of play on the prop shaft but the mechanic was unsure if this was significant or not.

My questions are:

2.Does anyone know how much play is acceptable in the prop shaft ?

The car is a 2000 A4 2.8 Quattro with 88,000 miles.

Thanks in advance,

Richard