Heater Assy, Defrost SVCE (590, 680, 690)
  590     Use Regardless of Serial Number.
  680     Use Prior to Serial #1810000
          From Serial #1810000 to #2277174 see
          7016558. Starting With Serial #2277174
          See 3070230
  690     Use Prior to Serial #1810000
          From Serial #1810000 to #2269189 See
          7016558. Starting With Serial #2269189
          See 3070230