I went through the same thing when I installed my changer.
Early 1998 210's had non fiber optic changers and late 1998 210's had fiber optic changers. This may be why there are different brackets. My non fiber optic changer uses the second bracket ( black one ) in your pictures. The kit included the bracket, screws and top cover. The tabs on the bracket mount on the ledge of the well on the driver side of the trunk with the small rubber pads resting against the side wall of the well. The top cover with the MB logo attaches to the bracket with the magnets on the cover. I do not have the cover for the changer. This is a truly plug n play installation. GilleyBenzTech helped me in explaining about the fiber optic and non fiber optic systems. Hope this helps.