This is a Rectify Series drop-in speaker system for Kato SD40-2 locomotives. The speaker uses double-sided mounting-tape or a dab of adhesive to mount on the frame. The rear headlight light-pipe will need to be trimmed to the number-boards with an LED glued to it (much preferred over the stock lighting arrangement anyway) and the stock light-pipe mounting posts trimmed off.
 
An optional UFIT-9325 front-mount speaker can be added, which provides improved sound localization (especially the horn/bell) and greater possible overall volume.
 
The speaker comes fully assembled and tested.
 
Dimensions are: 13mmH x 18mmW x 36mmL