The rear suspension of a 124 has FIVE links on each side. In the picture you show, from top down, then right: thrust arm, camber arm, torque arm, & tie rod. The tie rod has a ball joint on the side that bolts to the wheel carrier and an eccentirc cam bolt thru the subframe. The lower control arm is not pictured.
At 138,000 miles you may not need all the links, or diff bushings. The torque and thrust arms are good starting point. They are cheap and require no special tools except the 12 mm XZN driver.