Prop/driveshaft problem

Hi
Recently purchased a TD4 2 ltr on a '54' plate and have noticed an in-frequent knocking noise coming from directly underneath the front seat area.
It only occurs when turning left or right in low gear with low engine rev'sand when there is a slight gradient to the road.
Could it be the start of worn prop/drive shaft rubber bushes???

Regards

I have exactly the same issue which only started last Sunday, i also find it does not happen if in reverese, it is in the garage at this minute once i find out i will let you know

i have just been told my issue which sound similar is the IRD unit mega bucks £1100 fitted