A heavy metallic knocking noise on full lock is a worn CV joint at the end of the drive shaft.
The driveshaft itself is just that, A heavy rod from the drive wheels to the gearbox. Unless something is rubbing against it it doesn't really make a noise.
The best idea is jack up one front wheel at a time and give it a spin, What you could be hearing is a worn wheel bearing, Brake disc back plate rubbing of the disc, a worn or defective pad.
Or it's coming from the other end of the driveshaft at the gearbox......Hope not !!!!