The rear quarterpanel is stepped down into the trunk jamb area,but it overlaps the drip trough peice and it is welded to the trough peice. The trough is the part with the numbers stamped into it. This peice needs to be retained on the car,unless it's rotted out. AMD makes the trough peices,both left and right. The numbers are stamped on the drivers side drip trough peice. The AMD replacement trough peices do not have any number stampings on them. If you are concerned about the car retaining it's original stampings,and the trough is rotted beyond repair,then you may have to graft the stamped section into the new trough replacement part. If you do have to do this,and the car is a valuable numbers car,I would photo document the process with before during and after photos. If you already cut the trough out,you may have to reinstall it. I never cut a car until I have the replacement part in hand.