what is the fuel propulsion where the fleet series (quantity) is 310-329 (20)?
CREATE TABLE "fleet" (
  "order_year" text,
  "manufacturer" text,
  "model" text,
  "fleet_series_quantity" text,
  "powertrain_engine_transmission" text,
  "fuel_propulsion" text
);
SELECT "fuel_propulsion" FROM "fleet" WHERE "fleet_series_quantity"='310-329 (20)';