As was mentioned, it doesn't have a VIN. Ford produces (and Multimatic manufactures) a line of purpose built Mustangs for the track. These cars have a serial number but not a VIN. In fact, if you go into a Ford dealer and try to buy a Mustang GT4 (or in the past a Cobrajet, etc) your salesman would most likely give you a doe-in-the-headlights look and think you were crazy. A savvy salesman would direct you to the parts department.
Like those cars, the MkII is lacking more than just a VIN. It's got none of the airbags and other compliant safety equipment. Remember alot was ditched for weight. It's not been submitted for crash testing. And that pesky EPA "Miles per gallon" rating? Not done. So lots of things prevent it from getting a title and tags.