Not to be a fly in the ointment, BUT, General Motors did own until a few years ago,
Electro-Motive, a diesel locomotive manufacturing facility. In fact, they were one of the driving forces in the changeover from steam to diesel locomotives.

But with GM under the "brilliant" management of the last 30 or so years the decision was made to get out of everything but passenger cars. Bye-bye heavy truck, transit bus, heavy equipment, Detroit Diesel, Allision Transmission. Except for Bob Stempel, for a brief time, there has only been "bean counters" at the helm since the early 80's. And the Board of Directors rubber stamped every stupid move they could make. I blame the board as much as I blame the Chairmen, each one of them. Fritz Henderson, no blame on him, he is the janitor to clean the mess up. I predict he will be shown the door as soon as reorganization is completed. Scapegoat so to speak.

Why was the decision made to divest of these divisions dealing with mass transit? Short-sightness and the pursuit of profits for stockholders, artificially enhanced by a influx of asset sale funds in my opinion.

I know I'm off track here, but GM lasted through the Billy Durant years [[a roller coaster ride for sure), two World Wars and the Great Depression, to be brought down by mis-management by ineptness.