Formula S
Things that might be left on a junkyard 'S' that you might look for are:
Rear Valance with cutout
swaybar and/or LCA with swaybar tabs
Tachometer
Engine parts (valve covers, intake, carb)
Here is info on how to tell if the car is an 'S' from the fender tag
http://www.earlycuda.org/tech/tag.htm