Re: A shot these good questions

I think the 487 on the San Juan story is bunk. I thought the 487 road the best of the 36's. I know it would run faster than the rest out of Antonito. I timed myself once at 27 mph headed west once.
487 was never set up with steam heat and air signal lines. If it ran on the San Juan, it did so rarely.
One the biggest factors in the rigidity of the 490's is the trailing truck design. the 480's used a Hodges trailer truck that used swing links as centering devices. This is a very flexible design, but allows the rear to wag its tail exspecially when you have 12 feet of locomotive hanging off the back of the trailer truck. The 490's used the trailer design used on the 470's which have horizontally mounted coil springs that center the truck. This makes the engine more stable, but also makes it much more rigid.