These are Rectify Series drop-in speaker systems for Bowser Executive SD30C-ECO, SD40-2 and SD40-2F locomotives. The speakers use mounting-tape or a strap of Kapton tape to mount and no modifications are needed to replace the factory speaker.
 
The current-production SD40-2s with built-in stay-alives use the BOWS-UNI1 speaker in place of the stock speaker, atop the capacitors. Simply nip two of the screw-rings off and strap it down like the stock speaker. There is room for a UFIT-9318 front-mount speaker behind the shell-lighting pins for a dual-speaker option! Pictures coming soon!
 
The pre-stay-alive SD40-2s only have room for the rear-mount BOWS-S402 speaker (unless you modify the factory installation).
 
The SD40-2F has room to add 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.
 
Earlier units use the Large 1.5 speaker harness. Current 2024+ models use the Micro 0.8 speaker harness. If you're in doubt, email me a pic of your motherboard connectors.
 
Videos
SD40-2: https://youtu.be/Gv_59aDSmLo
SD40-2F: https://youtu.be/b4ptEHEMz4Y
 
The speakers come fully assembled and tested.
 
Dimensions are: 10mmH x 18mmW x 27mmL