Kit: Zimo MX648 (hard wired) with YouChoos SugarCurve7 speaker, cab lights and crew

Careful disassembly - bogies out first, then plastic frame. PCB out.

Separate the chassis halves and remove the motor and shaft assemblies.

One of the curved-top style speakers will be the way to go, but which... here is a LimoCurve6 and a SugarCurve7...

The MX648 (with sleeve removed) will fit nicely where the PCB was. We'll have to take off all the wires and change them to come from the other direction so they don't hang over the end.

Speaker (SugarCurve7) looks like it could go in a milled section part-way along, so carefully mill down a little at a time until we find a fit where the speaker's curved top will be flush with the chassis top.

Put new wires on the motor, which we'll solder directly to the decoder later, so they can be trimmed to the right size. We don't want too many heat-shrink joins in the install as there just won't be space, so wires direct from source to destination will be important.

Reassemble the chassis, and connect the motor wires direct to pickups temporarily so we can test it all still works OK on DC control.

Speakers looks like a good fit still, so proceed... check that body still goes back on properly, and in fact it seems like a bit of space spare, so all good. Take the body off and we'll begin the decoder installation...

Cover most of the decoder in Kapton tape, except for the part where the wires will be soldered - we'll do these in-place as we want the wires to be as close to the required length as possible.

Pickups and motor wires first... then the purplse speaker wires. We're using the fine ESU decoder wire here.

We can test as we go along - at this stage, the decoder should run the motor and sound correctly. Ensure that the speaker is insulated underneath of course!

Perhaps the most complex bit of the install is to put the lighting control back in, and we're also going to add independent cab lights. From the original factory PCB, we butcher the row of 4 SMD resistors, which we'll reuse. One resistor will be for each end's lighting, and another one each for the pair of cab lights, so 4 is perfect.

Need to identify which side is the common for the resistors, and we add an old resistor leg across those terminals where we can easily solder the decoder's common positive (BLUE) wire.

Next to rewire the factory head/tail lights. Take out the original wires, as they are too short, and we want to use more meaningful DCC-coloured wires... blue for positive, white for white lights and yellow for red lights. There are no resistors here yet, so ensure to use one while testing them directly like this. The whites and reds at one end will share a single resistor, and the the whites+reds at the other end will share another resistor.

Drill small holes near the top of the bulk heads for cab lights. We use mini SMD white LEDs, glued in place. Add crew figures while we are here too.

Connecting up is simple enought... blues connect to the cut-up resistor board as already described. Decoder's AUX1/F0Fwd output connects to front cluster's white and rear cluster's red negatives. Decoder's AUX2/F0Rev output connects to front cluster's red and rear cluster's white negative. AUX3/FA1 (normally green wire) connects to the front cab light't negative and the AUX4/FA2 (normally brown wire) connects to the rear cab light's negative. Test it all to check direction and operation.

The key is to be neat and tidy with this install, as there is little room to play with. If you can do that, it is relatively simple and the space is ample for getting the kit in and the body neatly back on.

The finished beast...

Please note that these guides are provided as useful resources for you, as-is. YouChoos cannot be held responsible for errors in the information, or for any damage caused to your models or equipment if you choose to follow any of the steps detailed here.