All first gen Firebirds have the assembly plant code in the VIN. It is either U (Lordstown), N (Norwood) or L (Van Nuys). If every first gen built in the U.S. had a Pontiac engine no matter where it was sold, and every first gen was built in the U.S., then all first gens produced for sale had Pontiac engines. Find a first gen with a different assembly plant code or a documented engine code other than a Pontiac code and then we can have a topic to talk about.