I should add that the 3751 hit a top speed in it’s heyday of 103mph. The big articulated locomotives couldn’t manage much over 80, though they could do that with a lot more rolling stock behind them.
You are correct. The BigBoys were designed in the 30’s for Union Pacific. They were designed as 4-8-8-4’s as opposed to the Santa Fe 3751 which is a 4-8-4. The BigBoys had two sets of 8 driving wheels. They were designed to pull a 3600 ton train across a 1.14% grade. Top speed was around 80mph.
My Grandfather worked for Southern Pacific for nearly 25 years. He was an engineer on the Houston to El Paso route. He ran mostly freight as opposed to the passenger Sunset limited.
Lots of great stories he could tell. Thankfully I managed to get most of them on tape before he passed away. His name was Rabbit because he liked to run fast. He started out as a brakeman but eventually worked his way up to engineer. I still have several of his old log books and watches. There is a lot of history there.
Its good to see the Santa Fe 3751 back up and running.