Here are some of the concept pictures from The Complete Book of Mustang:

Early in the styling process, you can see the Fairmont design relationship.
(Glad the top design didn't make it or the Mustang would have been confused with the Chevy Monza.)

 

And more pictures, now moving into 1975:

(What were they thinking? At least they were getting closer with the bottom concept.)

 

...Now in 1976, it looks a lot more like the Fairmont again!
If Ford had built this design, would the Mustang still be around today?

(Top right is a two-seater design.)

 

ah those are ugly i must say, but cool to see where it all started

 

Yeah, the bottom one looks like a squared off Mustang II.

 

Mixed with a Granada.

 

WOW... They look crazy. Cant say that I like them though.