Knocking
3 Answers
The crankshaft can cause a knocking noise, actually the noise is made by the rod when it looses "grip" on the shaft. The noise becomes louder as the revolutions of the engine increase; when the engine is cold (morning) the sound will be loud because it takes a moment for the oil pressure to reach the rod bearing, then it will level off. However, other parts of the engine can cause a knocking, or similar noise.
Sorry, if you are referring to the drive shaft, yes, a bad U joint may be the cause of the noise like F_O_R says.