In the previous postings regarding the CORNELL and the CAPMOORE, I forgot to include the Lehigh Valley tug BETHLEHEM. I believe this vessel is still around, she was operated by Turecamo towing and is probably now owned by Moran Towing. She had been quite extensively altered from her railroad appearance by rebuilding of the pilothouse and installation of a Turecamo designed stack, and did not look very much like a railroad boat in recent years (unless you took notice of the very heavy protective rail around the hull, which is pretty much a giveaway that the tug was built to work between carfloats).
If you have a current name of the tug in question I might be able to find
it along with a photo if its still working. I have a book that lists all of the ships and tugs used on the Great Lakes. I also have a large list of Ocean going ships and tugs as well.
for now here is a link to check out: http://www.morantug.com/ go to there photo gallery they own 4 tugs 1 out of the 3 is vary narrow she might be the tug you are looking for.