Kit: Zimo MX648 with YouChoos SugarCurve7 speaker

Dapol's Class 33 diesel is an excellent starting point once again, the only complication over previous models is the switch underneath to turn off the red tail lights.

As is normal for recent Dapol diesels, the lighting is attached via mini plugs. We will remove these to create as much space as possible for the sound decoder and speaker. The lights will be hard-wired back in and we'll add cab lights too.

Note the switch underneath for disabling the red tail lights. We will need to re-use this to retain the feature.

Here is the chassis stripped of all wiring - we will solder our decoder wires direct to the motor terminals and pickups later - the fewer joins we have, the better, as space will be at a premium.

Remove the 6pin socket board, and unsolder wires from the underside switch.

Disassemble everything so we have the metal chassis separated, ready for milling - to create space for the speaker.

Chassis before milling... and after milling...

Test-fit the SugarCurve7 speaker for size - looks like it will be comfortable... that's good, as it will leave enough space for wires to route around it later.

Add our own wires onto the underside switch so we can make use of it ourselves.

Solder some wires (orange and grey) to the motor terminals. These are new wires - thinner than the decoder's, as we will be replacing the standard decoder wires with these, to create as much space as we can.

Stick the decoder in final position now and start re-wiring... we have removed the decoder's original heat shrink wrap and replaced with our own Kapton tape, as this is thinner, and we needed access to the solder pads to swap the wires anyway.

Add the speaker in. Mounted on electrical tape first, then thin double-sided tape to hold it down. Now would be a good time to test motion and sound. Note from the side-shot that we have plenty of space above the decoder for our lighting wire joins.

4 SMD resistors from the original PCB are put in place for the lighting. One side is common, so we join that to decoder BLUE, common positive.

New wires on the model's lighting boards. Join up positive blues via a resistor - 1 for front light board, 1 for rear board, and 1 each for each cab light that we have also added (not shown)

Tidy everything up, test, tape down and slot body back on!

The completed article

...and another similar one...

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