Lm2 block heater. 6L LB7/LLY/LBZ/LMM/LML Duramax trucks. - OEM GM Part #: 84564686. BackWoods Diesel performance parts for FORD Powerstroke, Dodge Cummins, & Chevy/GMC Duramax. There is a bulletin, Software fix will be coming, but haven't heard that it's alive yet. Montana Winters have been a breeze with it. Last year a couple of times I noticed the GFI circuit blow in the garage but never knew why. This cord is essential for cold-weather starting and proper function of the engine block heater on GM 1500 trucks equipped with the 3. Shop at DmaxStore for your Duramax needs. Feb 7, 2012 ยท salesman said on delivery,, theres no block heater?? do they or not have a block heater and if so,, where is it. Hit the button, and the glow plugs will heat the engine pretty quick, and then the truck starts right up. zeoewy1nwa6ccqop1oawlx7argvogqfivndmssbi3enza1v