The LMM Duramax refers to Chevrolet Silverado HD and GM Sierra HD trucks equipped with the 6.6L Duramax diesel engine between the years of 2007.5-2010. It was very similar to the LBZ, but it featured an all-new emissions device, a diesel particulate filter. While it reduced emissions output drastically, the DPF system on the LMM resulted in these trucks having terrible fuel economy. This is mainly because of the post-injection regeneration method used. The DPF system and the regeneration process it undergoes is one of the LMM Duramax truck’s biggest problems. Despite the DPF system, the LMM Duramax is still a reliable and capable diesel.