Drive Shaft worn?

[Willem Lurker Find all posts View Profile Close Willem]

I have noticed I have a knock when I change gear and it sounds like it is coming from my drive shaft going to the back wheels. Has anyone notices a similar problem yet with their drive shafts? I have done 340000 km on mine now and the service technician says there is "play" on it and the worn splines are causing the knock when it takes torque.

Any ideas / experiences or is he yanking my chain and wanting me to replace for no major concern?