Lately i have noticed the rear of my '82 300SD looks quite a bit lower than the front. I have a subwoofer box with 2 15" subwoofers in it but its only about 40 lbs. Also the left rear tire is wearing on the inside pretty rapidly, i have been hearing a slight metal to metal rubbing coming from the back, you can hear it when you go by gaurdrails and buildings. I suspected worn wheel bearings but i just jacked it up and there is no movement in the bearings. It must be the brake pads going, there are no grooves in the rotor so i will check those out tomorrow, i have a set of new ones in the box. Also when i put weight on the back it goes down pretty easily, and the shocks are still good it has no bouncy feel to it.