CREATE TABLE table_name_55 (chassis VARCHAR(255), points VARCHAR(255), engine VARCHAR(255), entrant VARCHAR(255))
What is the chassis of Officine Alfieri Maserati with a Maserati Straight-6 engine and fewer than 6 points?
    
SQL: SELECT chassis FROM table_name_55 WHERE engine = "maserati straight-6" AND entrant = "officine alfieri maserati" AND points < 6