https://www.conceptcarz.com/profile/21664,24908/1963-pontiac-grand-prix-x-400-concept.aspx

In 1962, GM Styling built the 1963 Pontiac X-400 Convertible out of a stock Catalina Convertible.

The X-400 has a supercharged 421 Pontiac engine built by racer Mickey Thompson.

One X-400 show car was built each year for 1959, 1960, 1962, 1963 and 1964.

Only the 1963 and 1960 X-400s survive.

GM Vice President of Styling Bill Mitchell supervised the construction of the 1963 X-400.

It is understood that he and other executives used the car occasionally on the street.

The car was exhibited by GM at the Los Angeles and Chicago Auto Shows.

It was also used for 2 episodes of the TV series 'My Three Sons.' After GM was finished exhibiting the car,

many of the special parts were replaced with production model parts and the car was sold to a Pontiac dealer,

who then sold it to a customer.

The car was driven hard for many years in the rust belt and was then parked in the open for many years.

The 1963 X-400 was restored by its current owners who purchased it in 1981.

With the owners doing the majority of the restoration work in their spare time, the restoration process for the car began in 1982.

It made its first public restoration appearance at the 2015 Amelia Island Concours d'Elegance.

The restoration was completed in late 2014.