Athearns Southern Pacific tunnel motor is a sight to be seen and is a solid locomotive. I go through the history and how we came to tunnel motors in general

Sources

a title="Joseph Zadeh, CC BY-SA 4.0 <https://creativecommons.org/licenses/..., via Wikimedia Commons"

href="https://commons.wikimedia.org/wiki/Fi..."img width="512" alt="SD40-2 vs SD40T-2"

src="https://upload.wikimedia.org/wikipedi..."/a

Marty Bernard from U.S.A., Public domain, via Wikimedia Commons

terry cantrell, CC BY-SA 2.0 https://creativecommons.org/licenses/..., via Wikimedia Commons