My 1998 ML320's battery is dead.

I disconnected the cables and proceeded to remove the battery but could not locate the bolts to loosen the battery for removal. I looked and looked but could not locate any removal bolts? The battery appears to be held in by a bracket going over the top of the battery with a plastic clip.

I would greatly appreciate any advice on how I get this battery out. Also, should I go with the MB or Sears battery to replace it with?

Thanks for the suggestions.

John