I have a 2012 V6 auto with 54,000 miles. Late last summer I began hearing a thumping noise seeming to come from the left rear, then a few weeks later the same noise coming from both rear sides when driving on rough roads or hitting a bump. Seems suspension related. It sounded to me like the rear shocks were worn out, so I bought two new Motorcraft factory style replacement shocks, installed them and still had the same noise. I put the car up on my lift and examined any possible problems....bad bushings in the locating arms, sway bar, etc. Nothing appeared loose....exhaust system, fuel tank, etc. I took everything out of the trunk that could possibly rattle, drove the car.....noise still present. Noise is definitely louder in very cold weather. Anyone have a similar or same problem? or suggestions?