Is there a difference between the K19AT-18 and K19AT-18H

As an OEM York furnace part

this adjustable motor band typically fits standard NEMA frame sizes used in various furnace motor mounting applications

67" WC (Water Column)

This part is functionally identical to the 32000085-001/B

Hydrolevel 45-348 Wire Harness Is there a difference betweenThe Hydrolevel 45 348 Wire Harness is a specialized electrical interface designed to facilitate a direct communication link between a Safgard Model 1100 Low Water Cut Off (LWCO) and the United Technologies (UTC) Integrated Boiler Control Module. This heavy duty harness is essential for HVAC technicians installing 24V residential boiler safety controls, providing a plug and play solution that eliminates the need for field splicing or complex terminal