If the Chieftain's greenhouse looks familiar, that's because it was also shared with '55 Chevrolet 150, 210, and Bel Air two-door sedans both stateside and in Canada. The long-standing GM practice of sharing certain body shells between different makes maximizes tooling investments and streamlines the manufacturing process. Naturally, quarter-panels, hoods, front fenders, bumpers, and other bolt-on items are unique to each make, but the Chevy resemblance is clear right down to the characteristic beltline dip just beyond the B-pillar. Detail differences abound; notice how the Pontiac's fuel fill door opens upward (thumb depression on bottom of cut line). On same-year Chevys, the fuel door is hinged differently and opens horizontally toward the front of the car.