You may find pics of red coloured rally cars, but it was never a production colour for the 3dr road cars. There was possibly A/couple of pre prodution cars done in red. I remember meeting a guy with one nearly 15 yrs ago (maybe longer) who I asked if he'd done a convertion from a red 3dr sierra or resprayed a cossy. He said "no, it came that colour from ford". He actually didn't like it, he wanted to spray it black, but as it was from the factory he was reluctant.
The base model sierra 3dr came in Cardinal red, I know, I had one. which I scrapped