Posi Clunking When I Make Sharp Turns

I just remembered -- Just prior to taking the car out of the garage, I had it up on jack stands, to replace the speedometer gear, and I started it, and put it in gear to check to see if the speedometer worked, wo no jerks etc. Obviously, during this, it was free wheeling up to a reading of aprox 50 MPH, on the speedometer. -- After I took it out onto the road, this is the first time that it clunked, when turning sharply. -- Prior to this, I had ran the car for several miles, over a couple months, with no clunking. -- Could this have caused the clutches to rearrange, or ???