The different arm rest styles are due to a change from early to later versions in the chassis. Early version is the split in the middle, later is the push back wood.

Everything in my early style 2005 which has a small chromed bar indicates to push on the bar and there's a compartment hidden inside. In the console houses a 6 cd changer and 12 outlet/ashtray. Next to the glove box is a sunglass holder sized box which comes straight out. Next to the split armrest box is a drink holder. My padded top split box armrest holds a phone. I'm going to remove it and put a bluetooth unit there- they are sold on ebay and they are MB OEM units.