Noise at about 30 mph +?

Hi I have a transit t280 fwd transit 55 reg.
I have a noise which comes on at about 30 mph and then follow up or down. Still the same if I free wheel. I have jacked the front of the van up. And turned the wheels. There is a clicking noise from gear box when turning each wheel the clicking is the same from each wheel. Can you help please.
Cheers Kev.