A few points I'd like to make:
There are 2 sealing rings which must be replaced when doing this, one aluminum and one copper. The aluminum one is for the torque converter plug, the copper one is for the trans pan plug. On the torque converter, make SURE the old aluminum one is removed, it may stick to the torque converter and be difficult to remove. Sometimes it sticks to the plug, but the most problem I have is when it sticks to the torque converter, which happens more often. The torque spec on both plugs is 14nm. The torque spec on the trans pan bolts is 8 nm, I usually bump it up to 10nm. On an older Benz like this, you may find it beneficial to chase the threads on the transmission case for the trans pan bolts. I believe these are M8X1.25 bolts. The aluminum can start getting corroded on these bolt holes and cause it to be difficult to get the pan to properly squeeze the gasket into place. Sometimes it can make it hard to get the bolts threaded back into the case at all!
When putting in the fresh ATF, put in 2 or 3 quarts, then start the engine, then continue putting in the rest of the fluid with the engine running. Otherwise you will overfill the case and it will run out the breather, because the torque converter holds so much of the fluid and the pump won't pump it in there without the engine running.
To align the torque converter with the access hole in the bell housing, MB Stars method will work, I usually turn the engine over by hand using a socket and breaker bar on the crankshaft front bolt, but it may be difficult for you to find the tools required to do it either way, specially on a Diesel.
Another simpler though more frustrating way is to have an assistant "bump" the starter while you watch the access hole and torque converter drain plug to coincide with each other.
Gilly