From inside (document excerpt):
Coupling Box Kit Cancels: IIK 340M-40-63 IIK 340M-40-79 4-01 Installation Instructions Part No. 320721-761, -762, -763, -764, -765, -766, -767 and -768 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 would 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. 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 coupling box kit to replace failed coupling box assemblies. This coupling box kit contains the following items: Coupling box assembly Cold spot baffle Screw (No. 8AB X 1/2-in. long hex head) Installation Instructions INSTALLATION Step 1–Remove Whole Cell Panel Assembly See Fig. 1 and 2 for furnace component locations. See Fig. 4 for expanded view of heating system components. NOTE: Actual component location may vary depending on model and series. 1. Turn off gas and electrical supplies to furnace. 2. Remove main furnace door. 3. Remove blower access panel. 4. Disconnect field power wires from J-box. 5. Remove 2 screws securing J-box. 6. Remove 2 screws securing top filler panel and rotate upwards to remove or allow the whole cell panel to be removed from front of furnace. 7. Disconnect combustion-air intake pipe from intake housing and move pipe out of way. 8. Disconnect gas supply pipe from gas valve using backup wrench. 9. Disconnect vent pipe from inducer housing by loosening coupling clamp on inducer outlet.