The torque converter holds much of a automatic transmission's ATF supply. MB, unlike most manufacturers, has a drainplug on the torque converter. There is an opening in the bottom of the bellhousing to access this plug, but the engine needs to be rotated with a breaker bar and I believe a 1 1/8" socket on the front nut on the engine (clockwise only, as viewed from the front) to align the drainplug. You COULD try having someone "bump" the starter while you watch for the plug, but it's quite frustrating. The drainplug requires a 5mm allen socket, as does the trans oil pan. After allowing all the fluid to drain out of these 2 points, the pan itself is removed by taking out the 6 pan bolts. As a hint take out the 3 on the right first, then the left, this allows the right side to "sag down, allowing the extra fluid to drain out of the drain hole. After removing the pan, you'll want to clean and dry the inside of the pan to remove accumulated sludge. The filter is easily replaced by removing the 3 phillips head machine screws, make sure the 2 small cork gaskets come off with the old filter and don't stick to the valve body. After installing the old filter, then just replace the pan using a new gasket, the torque on the pan bolts is about 10 nm, and reinstall the drainplugs, the copper one for the pan, the aluminum for the torque converter. Make sure the old seal on the torque converter is removed. Torque on the dranplugs are both 14nm. The transmission oil capacity is listed in the owners manual I believe, it's at least 6 1/2 quarts. Put in a couple quarts (DexronIII/Mercon ATF) and start the car, then put in the rest with the engine running.