The last step to complete your Grand Prix window motor and regulator replacement is just to re-attach the plastic door panel. Make sure that all the ribbed plastic fasteners are straight and in the correct places on the back of the panel. Nothing looks worse than a sagging door panel.

Line up a few of the fasteners at the top and push them partially into the holes. Then line up the clip for the tweeter housing and the other fasteners on the sides and bottom before pushing them all in.

You'll hear a popping sound when you push them into the metal holes as the plastic ribs seat themselves.

After you make sure that the panel is flush all the way around and each fastener is properly seated you can screw in the two Torx screws. I used a little piece of tape to keep the screw on my Torx T-27 screwdriver so that they wouldn't fall down into the panel.
 

Finally, pop the little round plastic covers back on the holes and you're done!

It's much nicer driving my vehicle around with all four windows working again. My Grand Prix GTP may be a fast car with a powerful 3.8 liter supercharged V6 engine and sleek curves, but with a broken driver's window it makes me feel like I'm driving a piece of junk when I pull up to a drive through window.

Hopefully this repair guide has been helpful to you during your power window motor & regulator replacement on your W-Body style Regal, Lumina, Cutlass, Monte Carlo, Intrigue or Impala.