Recently I was reminded about the two different style of passenger side trap door frame panel used during 1966 production so thought I would take a closer look and post.
For reference and to define the different panels I offer the two below. Location of panel to help understand its location and relationship to other panels in a 66 fastback
On one the panel is basically flat with a few edge bends to help it smoothly attach to the surround panels.
The other version was stamped with a depression or dimple stamped in the upper surface of the panel as shown below.
If you have 66 fastback with original sheet metal please feel free to post the style of panel your car has if built at Dearborn during 1966 production.
Please remember this thread is for a specific plant and please include the VIN or partial VIN so we can graph and compare.