From inside (document excerpt):
Condensing Heat Exchanger Kit Cancels: IIK 340M-40-77 IIK 340M-40-89 9-05 Installation Instructions Part No. 330540-751, -752, -753, and -754 NOTE: Read the entire instruction manual before starting the installation. This symbol indicates a change since the last issue. SAFETY CONSIDERATIONS Installing and servicing of heating equipment can be hazardous due to gas and electrical components. Only trained personnel should install or service heating equipment.
Untrained personnel can perform basic maintenance functions such as cleaning and replacing filters. All other operations should be performed by trained service personnel. When working on heating equipment, observe precautions in the literature, on tags, and on labels attached to the unit. Follow all safety codes. Wear safety glasses and work gloves. Have a fire extinguisher available. Recognize safety information. This is the safety-alert symbol. When you see this symbol on the furnace and in instructions or manuals, be alert to the potential for personal injury. Understand the signal words DANGER, WARNING, and CAUTION. These words are used with the safety-alert symbol. DANGER identifies the most serious hazards which will result in severe personal injury or death. WARNING signifies a hazard which could result in personal injury or death. CAUTION is used to identify unsafe practices which may result in minor personal injury or product and property damage. NOTE is used to highlight suggestions which will result in enhanced installation, reliability, or operation. COMBUSTION-AIR INTAKE CONNECTION GAS VALVE AUXILIARY JUNCTION BOX VENT OUTLET CONDENSING HEAT EXCHANGER (BEHIND CELL INLET PANEL) PRESSURE SWITCHES INDUCER MOTOR CONDENSATE TRAP MOTOR AND BLOWER ASSEMBLY AIR FILTER AND RETAINER A01026 BURNER ENCLOSURE PRIMARY HEAT EXCHANGER (BEHIND CELL INLET PANEL) CAP AND CLAMP (UNUSED DRAIN CONNECTION) VENT OUTLET CONTROL CENTER BLOWER ACCESS PANEL SAFETY INTERLOCK SWITCH Fig. 1–Fixed and Two-Stage Models occurring) and RTV sealant (G.E. 162, G.E. 6702, or DowCorning 738) are needed before starting installation. DO NOT substitute any other type of RTV sealant. G.E. 162 (P771-9003) is available through RCD in 3-oz tubes. DESCRIPTION AND USAGE Use this condensing heat exchanger kit to replace a failed condensing heat exchanger. This condensing heat exchanger kit contains the following items: ELECTRICAL SHOCK AND FIRE HAZARD Failure to follow this warning could result in personal injury, and/or property damage.