My C4 has been working properly...until yesterday. It suddenly has no drive or reverse. When I shut off the engine, I can hear something near the front of the trans making a slight grinding noise for 1 second or so after the engine stops turning. I don't have a pressure gage so I can't check the line pressure. I pulled pan and the valve body to look for stuck valves in the VB (all OK) and to see if I could determine what was making the noise. I did notice that I could turn the input shell by hand when I had the VB off. I thought the input shaft splined into the input shell, and that it would not turn unless the engine was turning??? Is it possible that the input shaft has slipped out of the input shell??? I don't think I have a broken input shaft, as the last time I drove it, it was just around the block a few times to check my carb tuning. Any ideas before I pull the trans to see whats going on?