I have a Charger, but I was able to find the top of the roof channel to rear window section, from Tony's Mopar parts, of all places. I only needed a 4 inch section on the top right, but it worked out GREAT, and for $30 bucks was well worth the cost. It may be worth checking out Tony's Mopar parts to see if he has anything for your Roadrunner. I couldn't find a good photo of the part, but here it is, with the new part just laying in place, before I cut out the small section I needed, and fit it in place. On the lower section, I had to fab up the part I needed. I could have done like others have suggested, and bought a dutchman panel, but for the small part I needed vs the high cost of the dutchman, I was able to modify the leftover part from the top window repair. Good luck!!!