Alright so I'm having some troubles with my 74 Dart Sport. The noise is from either the drive shaft, or the 7 1/4 rear end. I'm not sure exactly what it is yet, but I did record a 24 Second video of what is happening. Around the 15 second mark you will hear the clunking/slapping sound. This usually happens when turning or accelerating from a stop and goes away around 30-40mpg. I plan on opening up the diff, but I also tried shaking the front and rear of the drive shaft. The rear drive shaft feels solid, but there is a tiny amount of movement in the front u-joint. (I'm not sure what's acceptable) What am I missing here? Is my differential toast or do I have a bad u-joint?