user: Question: What chassis was used by Roy Salvadori?
Columns: ['Entrant', 'Constructor', 'Chassis', 'Engine', 'Tyre', 'Driver', 'Rounds']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Porsche System Engineering', 'Porsche', '787 718/2', 'Porsche 547/6 1.5 F4', 'D', 'Jo Bonnier', 'All']
SQL:

assistant: SELECT "Chassis" FROM "Table" WHERE "Driver" = 'Roy Salvadori';