Heljan/EFE Class 58 Sound Fitting
Despite its narrow body, the Heljan 58 has plenty of space for sound with one or two speakers.
Start by prising off the body, there are no screws, just clips that hold it to the chassis.
To save trying to study photos of them later, make a mark on the chassis and body at one end so you get the body the right way when refitting it!
Use black tack to hold the wires in place, there are little channels in the chassis where the wires should go but in most models they are just floating above the flywheel and drive shafts.
Fit the decoder, pin 1 isn't marked, but the image above shows the correct way round.
Use black tack to hold a speaker to the roof at each end of the model, right behind the cab. If using one speaker it can go at either end.
Use tape to hold the wires to the roof, this helps to keep them out of the way when refitting the body. hold the decoder onto the chassis with tape. Re fit the body and the sound is ready to use. Here's an example of a model fitted with Legomanbiffo sound. Find Sound for this model here.