Okay, here you go. A couple things to note; it's pretty difficult to get a good measurement from a stamped feature with a large radius like the simulated quarter brake-ducts as you requested. Instead, I chose to use the front edge of the quarter panel at the door opening as my first reference point. I'll call that the 'x' axis. I then used the peak (or center) of the body line that runs through the middle of the badge and has the holes on either side of it and will call it the 'y' axis. This feature probably was not the best to use, but it was convenient and the margin of error is better because the holes are not very far off of it.
I did take a couple pictures of the hole placement but they really aren't much help. If you want, I'll be happy to send them but I'll have to do it from my work computer as I'm having problems getting my camera to talk to this one.
Finally, if you come across an 'official' drawing of the hole locations and it is different from these measurements and you have already put the holes in your panels, well,....sorry. All I can tell you is my car is a legitimate R/T and these are where the badge holes are on it.
Driver Side:
X-Axis, distance from door edge of q-panel to centerline of 'R' hole: 21 9/16 inches.
X-Axis, distance from door edge of q-panel to centerline of 'T' hole: 24 5/16 inches.
Y-Axis, body line peak to centerline of 'R' hole: 13/16 inch.
Y-Axis, body line peak to centerline of 'T' hole: 9/16 inch.
Passenger Side:
X-Axis, distance from door edge of q-panel to centerline of 'R' hole: 24 1/16 inches.
X-Axis, distance from door edge of q-panel to centerline of 'T' hole: 21 5/16 inches.
Y-Axis, body line peak to centerline of 'R' hole: 13/16 inch.
Y-Axis, body line peak to centerline of 'T' hole: 9/16 inch.
Let me know if you have questions or need further explanations on these measurements.