Actually, the steamer is a UP 3900 series Challenger type, a 4-6-6-4 under the Whyte notation. A Big Boy is a 4-8-8-4. One big spotting difference between the two is the 3900’s have the shield on the smoke-box door, where on a 4000 series Big Boy, the shield is below the headlight. It’s a common mistake we all make, since the two look so similar. Top speed? Maybe over 60mph, since the UP used a few in enger service.
Good eye, I didn’t spot that.
Still only a top speed of 70.
I already said that
It’s a sd70 ace
The BNSF is an SD70ace