That is a good catch Steve. Neither of the resin Demons I have have the trunk ridge.
I am trying to find a set of clear head light lens for this one.
The trunk lid center "ridge" was a mid-'71 change. Cars newly constructed for the '72 season would probably have it, while teams stretching '71 cars into the '72 season might overlook the change.
The MPC kit parts don't fit all that well, so it's not surprising that resin kits based on it are also tough to get together. MPC didn't get the front wheel openings right either. I found out about the poor fit while reworking a '76 Dart body to accept some resin front end parts copied from the MPC Demon kit. From a resin kit that I bought second-hand (don't know who made it), as of now all I'm using is the taillight panel (cut from the body) and the front bumper/grille (and I might set that aside in favor of a Modelhaus part, as I did with the hood and front pan).