Part Number: 145R20039 (Aft rotor head)Part Number: 145R200416 (Aft rotor head)Part Number: 145R200418 (Aft rotor head)Part Number: 145R20042 (Aft rotor head)Part Number: 145R200420 (Aft rotor head)Part Number: 414R2002 (Aft rotor head)Part Number: 414R200241 (Aft rotor head)