while 49K0301 is the updated catalog iteration of the same valve

the R-B terminals open high (for heating) and the R-Y terminals open low (for cooling or circulator control)

and they are interchangeable in all documented Lennox technical manuals

this HVAC jackshaft hardware provides the necessary mechanical linkage to maintain accurate blade positioning across multiple sections

ensuring a consistent arc for rapid fuel ignition

Nordyne 493214R Heat Exchanger R-410A while 49K0301 is the updatedThe Nordyne 493214R Heat Exchanger is an OEM primary heat exchanger engineered specifically for Nordyne gas furnaces and M1MB series indoor units. Designed to meet exact factory tolerances, this aluminized steel heat exchanger ensures efficient thermal transfer while maintaining structural integrity under high cycle stress. As a direct HVAC replacement part, it addresses common failure points such as stress fractures or combustion byproduct buildup