Group II Mustang - Race

[98SVT - was 06GT]

Also, don't understand why Ford could not use fastback Mustangs in the early Trans Am series, as they were production four seaters? Ford did so in 1969.

I had heard at the time it had to do with the rear side windows. These were sedans and as such needed a rear window that the Fastbacks - until 1969 - did not have. It would take a deep dive in the FIA paperwork to find the original requirements (not the papers the manufactures sent in those just say they met the rules). I haven't been able to find those early papers online.