This is a Rectify Series drop-in speaker system for sound-ready/equipped Walthers Mainline RS2 locomotives. The speaker uses the factory screws to mount and no modifications are needed to replace the factory speaker.
 
If you need a 2-pin speaker wire harness, these use the "small" size: https://www.scalesoundsystems.com/product-page/factory-pcb-speaker-harness-small
 
The speaker comes fully assembled and tested.
 
Dimensions are: 10mmH x 18mmW x 30mmL