Sorry about that. Here is a pic.
Is is pictured on the right side of the loco(to the right of 2802). I think MTH put these on some of their B units to provide easier access to plug the male tether connection in. I am going to be pulling a fair amount of cars behind this and hope I don't get a runaway. Is there an MTH parts list anywhere for 20-2596-3 that I would be able to order a coupler like the one on the other end?
Go to the this link for the Pennsy 20-20398-3 E-8 B unit and zoom and hover over the end with the skinny coupler to get a better view.
https://mthtrains.com/20-20398-3
Thanks,
Chas