My car is a 1980 245. The last few days, I have heard an intermittent noise coming from (I'm 90% sure here) the left rear of the car. It sounds like thunder - like a grinding rotor. It comes and goes in spurts of around 5 seconds regardless of speed, and I hear it when accelerating or coasting. However, the sound goes away during cornering, or usually when I hit a good bump. My rear rotors and pads are good, and U joints are under a year old. Rear diff fluid is full, too. Seriously, this is loud - it sounds like you would expect a dragging muffler to sound. I know my rear bearings are a little long in the tooth, but I always heard that when the bearings start to go, you hear it when cornering first, and as a whining noise - not thunder. Is the noise I'm hearing totally atypical for a wheel bearing problem? Is it more likely in the differential, or something else entirely? Also, over the last few days its gotten worse - louder, and sticking around for longer (go figure). Any ideas would be greatly appreciated. Thanks, Jorge