For Suburban Furnace Models SF-20QT/ SF-25QT/ SF-30QT/ SF-35QT/ SF-42QT/ SF-20FQT/ SF-25FQT/ SF-30FQT/ SF-35FQT/ SF-42FQT/ SFV-20QT/ SFV-25QT/ SFV-30QT/ SFV-35QT/ SFV-42QT/ SFV-20FQT/ SFV-25FQT/ SFV-30FQT/ SFV-35FQT/ SFV-42FQT/ SF-20VHQT/ SF-25VHQT/ SF-30VHQT/ SF-35VHQT/ SF-20VHFQT/ SF-25VHFQT/ SF-30VHFQT/ SF-35VHFQT/ SF-T Replacement Cores; With 521099 Board And Rewiring Instructions