86' trans (A4LD) won't do anything

[Daveman]

I have an 86' Aerostar with the 3.0 engine. Everything worked fine until one day; when it went to shift into overdrive it slipped. It was like the trans was put into neutral or something. The trans wouldn't pull again until the engine rpm's lowered and the trans shifted back into 3rd gear. If I slowly reached high speeds OD would usually work fine. This happened about 3 days in a row. Then one day while driving to work; it was working fine and then the trans just slipped out of gear and wouldn't work at all, in any gear. Now when the engine is started; the trans won't work at all in any gear, and you can here a slight chatter from the bellhousing or the front of the trans. Any suggestions would be very appreciated. Thanks in advance.