Apparently any car older then 20 years if the manufacturer is gone, can be registered the same way as a vintage vehicle. I have verified it, but I think its unlimited mileage with no emissions and only a limited safety inspection.
I'm gonna call the dmv. tomorrow and verify. if so, my cougar plans might change a bit.
http://le.utah.gov/~code/TITLE41/htm/41_01a010200.htm
line 57.