Doe anyone have a diagram of the cylinder location/firing order for an 01 E320? Please help.

 

Looking at the engine from the frmt of the car cylinders 1,2,3 are on your left counting from the front, 4,5 and 6 on the right (Drivers side in the USA)
The upper coil pack goes to Plug A which is the plug nearest to the front of the vehicle on each cylinder. the lower coil pack to B.
Hope this helps.
On some MB cars the cylinder number is embossed on the camcover. Likewise A and B plug.

 

You don't need firing order. This is automatically looked after by the ECU.