This locomotive is from my father's personal collection. It has been in its box on a shelf for as long as I can remember (at least 30 years) and potentially longer. He doesn't remember when he purchased it, and for my entire childhood I remember this as being a Pennsylvania Railroad GP20 in the box.
I pulled it out to test it and to take pictures a few days ago and realized that it was originally painted in a Burger King livery and that someone actually custom painted it to PRR colors. As you can see in the photos, it appears to be very well painted, though you can still see the original Burger King logo if you look really closely with the right light.
I did put the locomotive on a test track and ran it back and forth a few times. I'm a model railroader, though don't have a ton of experience with Lionel/O27, so please see the video. It seems to run well, though. My cat wasn't super impressed.
If you have any questions, please do not hesitate to reach out and ask. I am more than happy to provide any information that I can.