Your post is confusing.

"When shifting into park, the car will roll around 6" - 8" either way depending on the grade upon which I'm parked. I use the parking brake regularly, shifting to neutral, then engaging the park brake, then up to Park."

If you actually always apply the Parking brake before you shift into Park, then the only way it can move 6 to 8 inches is if you Parking brake is not holding. You can adjust the Parking Brake system. As previous post stated, never use Park to hold the car.


Search forum on R to D delay or similar terms. You will find information about your transmission symptoms. First step would be to change the tranny fluid and filter.
There are shifter bushings that could be bad, cheap fix. There is the B2 piston problem.

Steve