Screw, #8-18 x 1/2" Hex Head
    NOTE: IF USING THIS SCREW FOR REAR DUCT SEE
          SERIAL BREAKS LISTED.  FOR ALL OTHER
          APPLICATIONS DISREGARD SERIAL BREAKS.
  501R    Use regardless of number
  501F    Use regardless of number
  511     Prior to #M1004775 except between
          #M964470-M964769. Starting with
          #M1004775 and between #M964470-M964769
          see 6201060
  532     Prior to #M/P1004775 except between
          #M964770-M965069 and #M990700-M990999.
          Starting with #M/P1004775 and between
          #M964770-M965069 and #M990700-M990999
          see 6201060
  550     Prior to #M/P1004775 except between
          #M964070-M964469 and #M984750-M985149.
          Starting with #M/P1004775 and between
          #M964070-M964469 and #M984750-M985149
          see 6201060
  561     Prior to #M/P1004775 except between
          #M965470-M965869.  Starting with
          #M/P1004775 and between #M965470-M965869
          see 6201060
  590     Prior to #M1004775 except between
          #M965870-M966269. Starting with
          #M1004775 and between #M965870-M966269
          see 6201060
  200/300 Use regardless of number