For 2005 the LGB range included, for the first time, three choices for going digital on some of their new locos. These include the Abe6 4/4 railcar which comes in the following three flavours:
Recently I had the oportunity to look inside one of the DCC ready locos to see how one would go about fitting a decoder.
One immediate conclusion is that this loco requires a 3 amp third party decoder, and the 55021 MTS decoder is not suitable. It also doesn't have a direct decoder socket.
The interface itself is ten pins arranged in a straight line, and provides the usual connections: 2 from the track and 2 to the motor. In addition, there are pins for the front and rear lights. There are also connections for F1 and F2. From the instructions, F1 appears to control the interior lights, which can be controlled independantly of the front/rear lights. Without actually fitting a decoder, I'm not sure what F2 does at this time.
In conclusion, if you are thinking about going digital in the future, it may be considerably easier to (if you can afford it), get the version with the MTS decoder already installed.
However, if you are comfortable with fitting third party decoders, or prefer using a specific type / manufacturers decoders, the analogue version might be the one for you. To get into the electronics area of the loco, you have to remove the entire yellow superstructure, which comes off as one piece.
There are two screws at either end of the loco, which can only be accessed by unplugging the vaccuum pipes. They don't completely come off, but can be pushed aside. At one end, there is also a third pipe which must be unclipped from the black undercarriage before the ends will left off.
Additionally, there are pairs of screws distrubuted underneath the loco. Off the top of my head, I think there were 8 in total.
One thing to watch is the doors, as they will fall out, just note which way round for when you put them back in. Also, the benches may come out, but they are reasonably well stuck in. As you lift the yellow cab, there will be a wire under each corner that will prevent you separating the two parts. They all just push to one side, but make a note of how they are placed for reassembly.
The electronics PCB is located in the middle of the loco, where the window is blanked off with a white screen. There is plenty of room here in the centre of the loco where you can install any decoder - it is fairly spacious.
Reassembly is straightforward, and can be made easier if you turn the cab (yellow) upside down, and upturn the chassis, and bring them both together. This especially helps with the doors.
Of course, if you want sound in your loco, and the LGB sound units are extremely good, you have no choice but to have the model with the MTS decoder and sound board.