I got 2 of these unique Bachmann SCL BQ23-7 diesel locomotives (the other had known shell damage) quite some time ago from microbusss. However, the USPS damaged both rear couplers and for the life of me, no matter what other coupler I tried installing, the BQ23-7 just kept derailing cars. :(
Then, I got ingenious. I installed yet another horn-hook coupler, and put a dab of hot glue on the bottom of it, to prevent it from coming off the screw on the coupler housing. Success!
Anyhow, please enjoy this video of it in action on the Ephrata Valley Railroad's outer line. Such a cool looking diesel -- so glad that Bachmann made a version of it.
https://www.youtube.com/watch?v=peKj_7yVhKw "Let your light so shine before men, that they may see your good works, and glorify your Father which is in Heaven." - Matthew 5:16