Sound Fitting The 21 or 8 Pin Bachmann Class 20
These are amongst the easiest models to sound fit, theres slightly more space in the 21 pin model than the 8 pin one.
Start by removing one screw from each end to remove the body
For the 21 pin model we recommend the slimmest double iPhone speaker
For the 8 pin model we recommend the 26x11x7 speaker
Find the decoders and speakers here.