CREATE TABLE table_57903 ("Entrant" TEXT, "Constructor" TEXT, "Chassis" TEXT, "Engine" TEXT, "Tyre" TEXT, "Driver" TEXT, "Rounds" TEXT)

Which chassis had an entrant of John Mecom?
SELECT "Chassis" FROM table_57903 WHERE "Entrant" = 'john mecom'
SELECT "Chassis" FROM "table_57903" WHERE "Entrant" = 'john mecom'