The usual culprits for a repeatable noise from the same area of suspension are drop links or one of the ball joints on the lower arm.
To give you an idea of price:
LH Lower Arm and Bush:
https://www.dmgrs.co.uk/products/rov...2500-rbj000371
Front Drop Links:
https://www.dmgrs.co.uk/collections/...inks-rbm100240
The key to running a 75 / ZT (or any car) without breaking the bank is to properly diagnose issues before loading the parts cannon.
The advice above is spot on - in addition, check both drop links for play (using a large flathead screwdriver or pry bar to move them) and the same with the lower ball joints.
Good luck!