ToyotaTacoma: TRD? SR5? 4x4 or 4x2? ?

I own a 2007 4x2 prerunner TRD. These trucks usually have a 6cylinder engine and do have a lot of clearance, in fact you would probably mistake it for a 4x4. My understanding of the TRD is if you get stuck for instance like mud you can push the on inside the truck which will allow both of your rear wheels to turn and help you to get out the mud.