Rear differential bushings

Today, my manifold broke as I was driving down the highway. The exhaust is extremely loud and obviously needs to be replaced or fixed. I have had the manifold fixed once before, approximately six months ago, because it did the same thing with the loud exhaust on the highway out of nowhere all of a sudden one day. It was welded together and fixed, until about a month ago I could tell the exhaust was getting louder little by little, and today I assume it actually snapped and broke once again. I was told that the reason it is breaking is because of the worn out bushings In the rear. Since my car makes a loud clunk noise when I shift gears (it is an automatic) and also shifts hard most of the time while I am driving it, which is because of the no good bushings. Does this sound legit? And is the bad bushing because of my exhaust problem?