Passenger quarter panel. This is the last fitting of the quarter. It will not be removed again. I will say for you guys that are doing full quarters on a road runner. The quarter fits pretty well. The area of concern is on the lower rocker where it is spot welded to the pinch weld. The angle isn't quite right and it is a little to long so when you clamp it in the pinch it would bulge the bottom out. I had to cut the lip and take about 3/16" off for it to line up. once its welded back in a ground you will not know but if you don't do this the quarter will not fit well.