SS 396, M 21, and 12 bolt rear with posi. A damn fun combination
The 1st owner installed the Sun Super Tach, had a fender bender and garaged the car for good. The 2nd replaced the seats, but a bad brake line kink was causing a real problem pulling to one side, causing the 2nd owner to garage it for a decade or two, now the 3rd has put on factory correct but not original hub caps... and the rest is basically original because the car was garaged forever. The article isn't clear on exactly how long it was stored in total. It has 90 thousand miles on the odo.
http://www.hotrod.com/cars/featured/1507-all-original-1967-chevrolet-chevelle-ss396-is-the-find-of-a-lifetime/