Since you've already replaced and resealed your diff, the only other main source of whining from the back of your car (besides that of your significant other when they see the receipt total) is likely a bad rear wheel bearing (or two). Purchase one or more of our kits and have all the parts needed to address one or two tired rear wheel bearings. This kit is priced and sold individually (1 bearing, 1 nut), as we are aware of budget constraints. However, we do recommend replacing rear wheel bearings in pairs.
E30 Rear Wheel Bearing Kit includes;