I once thought it might be the strut mounts. I replaced the shock absorbers at that time. However, I applied a generous amount of grease to the strut mounts and made sure the springs were properly seated against the stops during installation. I also checked again (verified the stops and the ends of the springs), but didn't find anything unusual. You could still try loosening the shock absorbers, perhaps apply some talcum powder, and then tighten them again. It should be fairly quick.
The following screws secure the rear suspension on a Golf III: 2 screws on the left and right sides that are visible (size 18 or similar), 2 screws that are accessible through openings in the control arm (also size 1

, and at the front, 2 screws on the left and right sides (size 16) that secure the front engine mount to the longitudinal member.