Knocking noise

Hi all
I have started to get a rhythmic knocking noise on my 74 T2.
It only happens when travelling, and increases/decreases in speed as I do. It doesn't happen when idling, and not all the time when travelling.
Any Suggestions?
Cheers
Rob

 

front or rear?

cv joint possibly

 

Front I reckon.

 

Think its a rear cv....not much to give a rhythmic knock at the front end.. no cvs and bearings don't usually knock..more a squeal or grinding noise. An expiring speedo cable/head will give a loud tick but the speedo needle will dance about too.

 

Thanks.