Failed Torsion Bar Suspension Linkage
This torsion bar linkage connects the torsion bar with the rear wheel assembly as part of the rear suspension. Notice the failed linkage points where the rubber booted joint is loose. This causes knocking as the torsion bar operates when going over bumps and dips. It’s a cheap and easy fix at about $20 for each of the two linkages, assuming you do the work yourself.