This is a Rectify Series drop-in speaker system for Bowser Executive SD30C-ECO, SD40-2 and SD40-2F locomotives. The speaker uses carpet-tape, a strap of Kapton tape or a touch of adhesive to mount and no modifications are needed to replace the factory speaker.
 
The SD40-2 has room only for the rear-mounted speaker (unless you modify the factory installation). For the SD40-2F, you have the option of adding a second, front-mounted speaker with the UFIT-9325-RC1. This is highly recommended as it greatly improves the sound localization and volume potential.
 
Note that the factory sound-files that come loaded on the SD40-2F have a big, full sound. You'll really appreciate the Scale Sound Systems speaker upgrade in these! The stock sound-files on the SD40-2 do not have as much low-frequency content, though a significant improvement in sound will still be realized with the speaker upgrade. You may wish to load a different ESU file in your SD40-2s to see if you like the sound better. My favorite Select/V4 file is 75432/76432. Favorite Loksound 5 files are S0732 and S0508.
 
Videos
SD40-2: https://youtu.be/Gv_59aDSmLo
SD40-2F: https://youtu.be/b4ptEHEMz4Y
 
The speaker comes fully assembled and tested.
 
Dimensions are: 10mmH x 18mmW x 27mmL