Get complete cold-weather support for your Duramax diesel with this Genuine GM OEM block heater and cord kit — featuring the upgraded GM Part #12742345 Block Heater and the matching Heater Cord #84766919. This combination ensures your 6.6L L5P Duramax stays ready for winter, with proper engine warming and a secure electrical connection from the heater to your truck’s existing wiring harness.
Updated OEM Block Heater
The GM 12742345 Block Heater replaces the older 12705875 design and delivers a direct OEM fit for late-model Duramax engines. Built to GM’s high standards, it installs quickly into the engine’s coolant passage and reliably preheats the engine for easier starts in cold weather.
Includes Genuine GM Power Cord
No need to source the cord separately — included in this kit is the GM 84766919 Heater Cord Assembly, designed to plug directly into the block heater and link up with the intermediate harness to complete the power path. This genuine GM cable meets OE electrical and mechanical standards and replaces older cord part numbers like 84537545 and 84660592.
Why You Need Both
A functioning block heater warms coolant and reduces strain on your diesel’s battery and starter in freezing temps — but without the correct cord, you can’t power it. This kit gives you both essential components in one place:
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Block heater that fits perfectly and performs dependably
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Heater cord engineered for proper connection and durability
