Got a 2001 Supercrew with a 4.6 and the 4r70w trans. Got 95,000 on it, and changed the trans fluid and filter at 30 and 60,000 miles. Trans seemed to run as expected, never had any issues with it. One day started from a stop, stayed in first too long,then hit second pretty hard, third seemed to shift ok. Got to a light, and it didn't seem to want to go into neutral. left the light and did the same thing. After two more lights, heard and felt a sevear grinding/cluncking sound that lasted threw first and second for the most part, then went away. Trans wouldn't find neutral, so I quit stopping for signs and lights and just rolled thru. Got it home and once in the driveway, it locked up with no reverse or first, like you had the wheels blocked. If you gave it enough gas, it move, but it sounded like ball bearings in a meat grinder. Truck couldn't even be moved in neutral with the engine off. Long story short, towed to a tranny shop for a full rebuild, TC and all, for the low price of $2800 ($2200 with company discount). They said it was the result of a bearing failure at the planetary gears. They gave me the gear cluster to keep, and there were small roller bearings embeded in all of the gears. The ring and planet gears were pretty much wasted. Like a said, never had a trans problem, this happened very abruptly. Never had a trans fault light blink threw the whole issue either. Has anyone ever sean or heard of this problem before, and what might have caused it?

 

That sounds VERY similar to what happened in my '94 CV, but it was slipping when I bought it, so I expected it to happen. When mine blew out, it wouldn't drive at all. Consider yourself lucky you were able to nurse it home.