I just bought a 2018 Dodge Ram 2500 mega cab with the 8.4 Alpine stereo system. I am reading that there is an 8" subwoofer included in this system but I cannot find it under the rear seat where it is shown in the standard cabs. I have the 60/40 reclining seats in the back due to the mega cab and there is nothing under those seats. Does anyone know where the subwoofer is located? I wanted to look into upgrading it.