87 4Runner Automatic Tranny Clunking

I have an 87 4Runner with an automatic tranmission on it. When I shift into gear I hear a rather loud clunk. Also, the tranny seems to be slipping a bit when Im shifting. Anyone know what may be causing this?

I cheched the fluid level and it is really high. I must have overfilled it a few months ago. I wonder if this could be causing some slippage.

I suppose you should find out. Let us know the results.