Fitting Sound And Stay Alive To The Bachmann 08
This is what I would consider a more advanced method of fitting sound to the 08, it requires removing the 8 pin socket and hard wiring the decoder, but it allows for a bigger speaker and means that the stay alive doesn't need to go into the cab.
We'll assume that you know how to get the body off (it's 1 screw and a clip under the cab). So we will skip to preparing the body and chassis. Take the circuit board, unsolder the 4 wires from the motor and pickups, and snip off the orange capacitors. Then unscrew the small weight from inside the body, and grind off the lug for it, as well as the underside of the exhaust.
Next you are ready to solder the decoder wires to the pickups and motor (red and black to the pickups, grey and orange to the motor. You can see which wires go to which side in the first photo if you aren't sure. Stand the decoder up at the front of the model and attach it using sticky dots or similar, but not black tack as it can melt. Stick the speaker behind the grill, but facing inwards towards the loco. The sound will escape through the exhaust.
All the parts can be found here: