A very simple install, the body lifts straight off the chassis, working from the long hood end. The full perimeter of a 16x25mm speaker is superglued to the chassis. An alternative is to fit an ESU 11x15mm sugarcube speaker in the cab.
In the example below the 8 pin plug has been trimmed and the wires soldered directly to the 8 pin socket, but this is optional. Some trimming of the inside of the bodyshell may be required within proximity of the speaker solder tabs.