From inside (document excerpt):
Inducer Housing/Motor Mount Replacement Kit Cancels: New IIK 330A-40-4 9-15-94 Installation Instructions Part No. 310348-755 and -756 NOTE: Read the entire instruction before starting the installation. SAFETY CONSIDERATIONS Installing and servicing 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. The inducer housing/motor mount replacement kit contains the following items: Inducer housing assembly Shaft seal Motor support Motor plate Screw Grommet Gasket Housing gasket Installation Instructions INSTALLATION Step 1–Remove Inducer Housing and Relief Box and Inducer Motor Assembly 1. Turn off gas and electrical supplies to furnace. 2. Remove blower and control access doors. 3. Disconnect and remove vent pipe. 4. Unplug inducer motor. 5. Disconnect wires from pressure switch and draft safeguard switch. 6. Remove screws securing relief box to top plate (upflow) or to blower shelf (downflow/horizontal). 7. Disconnect pressure switch tube from collector box fitting. Turn off gas and electrical supplies to unit before beginning any installation or modification. Follow operating instructions on label attached to furnace. Failure to follow this warning could result in personal injury or death. INTRODUCTION This instruction covers the installation of the inducer housing/motor mount replacement kit Part No. 310348-755 or -756 in all non-condensing, induced-draft furnaces in 40-in. cabinets. Replacement kit Part No. 310348-755 should be used with all units requiring a 4-in. vent connector; replacement kit Part No. 310348756 should be used with units requiring a 5-in. vent connector.