I just bought a 1969 cougar vinyl top the other day and the roof on it is completely rusted and needs to be replaced. Looking to see if anyone knows which roofs are interchangeable and where the best place to look for a donor car or someone who might have what I need.
1969 and 1970 roofs ( is the plural rooves ? just kidding ) are interchangeable. Nothing else - not Mustang, nor early or later years of Cougars. Interesting to note that your original ( was it factory ? ) vinyl roof had the chrome version of the vinyl-paint divider mouldings. It was my understanding that the chrome version ( the only other variations were matte black and white mouldings ) was used for two tone paint cars, or the 1970’s with the Hounds tooth patterned vinyl roof. The chrome version is NOT that common, as compared to the black or white mouldings.
Your vinyl roof ( what’s left / showing in your picture ) is black, so it should have had the matte black mouldings. Unless you have the Marti report to state that the vinyl roof was a factory original, I would wonder if it was added later, and the installer ( you can’t rule out a dealership in this case ) ordered and used the chrome version mouldings. If the vinyl was non-factory installed that might account for such a bad rust issue in the roof
Have a look at the WCCC videos - there is an excellent video [YouTube]https://www.youtube.com/watch?v=CDyBd9Wx1vk[/YouTube] detailing a 1968 White Cougar which undergoes a complete roof replacement ! It was done on Andrew Chenovick’s Cougar while he was at West Coast Classic Cougar.
Welcome to the Forum. Perhaps consider posting a wanted ad in the Parts Wanted section of this Forum for a roof section or donor car.
And, give your location or “near” location along with a distance that you’re willing to drive or have shipped to you.
Hopefully you will get some responses and find what you need. 
What i noticed with that video is that they just did only the top roof panel, where as on mine i would the A pillar and the C pillar as well which will be a harder job to get done.
That’s interesting. If you are meaning the divider moulding between the rear windscreen and the trunk lid?
My 70 cougar is green? That is, the moulding is green.
It had a green vinyl roof and the car is a light yellow/ green colour, well that is what is looks like to me.
Peter.