Knocking noise??

Hi all

my 1990 golf cabby 1.8 GTI has developed a knocking noise. Just as I'm pulling away and I'm getting the bite, there is a single knock. I was sure it was going to be a cv joint? Anyway on inspection tonight I expected to see a burst rubber gator or grease or something?? But nothing, can't find where it's coming from. Any help or advice would be great.

Thanks
 

Find a car park area, put the car on full lock and go round in a circle. I f you go to the left lock, and the knocking is louder, chances are your cv joint is worn, put lock on r/h and if that knocks then your r/s side is worn, it should make a  knock knock knock sound if its on its way out

Round and round in circles in the car park. Full lock left and right no nocking noise at all??

Now I'm confused to where this knocking noise is coming from. The search goes on.