My 71 Duster 340 trunk lid (no spine) has cut-outs, my 72 Demon 340 trunk lid (with spine) has no cut outs.
Both cars are 'untouched'....
The spine came in 1972 first, I believe to have read somewhere, that this innovation was necessary because of 'structural weakness' and therefore deformation of the trunk lid when closing...but I'm not sure about this explanation.
