Can anyone help me? I have just had my engine/gearbox rebuilt to race spec, and added a turbo. The garage that did the work forgot to put oil in the gearbox

. So when it went to be tuned the gearbox blew. So I got a new gearbox and Spoon plate diff, and replaced the damaged CV joints with new ones. The problem is every time I am driving slowly and I turn the wheels I'm getting a constant clunking sound from both sides of the driveshafts. Which would normally point to damaged CV's, but mine are new. My next step is to replace the shafts. The noise goes away when driving in a straight line.
Can anyone else suggest something that might be causing this?
thanks
Matt