See this? It's one of the early designs Ford cooked up as it planned the Mustang II. This one was based on the big platform used from '71 to '73, before Ford decided to go smaller, with a totally clean sheet. The design chronology is pretty wild.
Not all the early designs looked like they belonged parked outside Mos Eisley Cantina. This car, also based on the big platform, incorporates Mustang II cues you recognize. It's just more...gigantic. And good-looking, too.
Once Ford pivoted to the small platform, things didn't get any less weird on the way to the showroom. This is one of the first looks that was presented for the smaller car:
And that's just a taste of the stuff. We've got the history, plus a big slideshow of the designs that didn't make it.
Read the whole thing at R&T.
This is a rejected design for the Ford Mustang II. It was not alone.