Seeing this engine reminds me that I believe we saw it at the same yard/roundhouse on our trip in the summer of 1963. My family signed on to take this mostly railfan based group under John Vickers from Texas tour.
We had a section Pullman for the two weeks to Merida and back to New Laredo, TX.
Anyway there were about 20 people, mostly single aged guys and two gals who where with another couple, sorta like my brother and I with mom and dad.
Since my brother(8) and I(12), were the youngest of the bunch we were sorta left out by the big boys. So when in Mexico City, the guys told us they were going to some tourist spot that they knew we would not care for.
It was called Valle de Mexico. Well my dad could see through their fun, and said Boys, lets go see San Lazaro, where all the NG steam is. We went there to the roundhouse and saw a lot of action. we had ridden behind 268 from Pueblo the day before.
So a few years later we find out that we had been duped cause Valle De Mexico was the big main engine house and yard for the SG NdeM in Mexico City. Years later we ran into the tour leader John Vickers, and he apologized saying something to the effect "you two boys turned out to the most hard-core of the bunch", and we were wrong to do that to you.
On my way to the C&TS in 1976(Where I worked on building that caboose), I stopped to see John in St. Joseph, MO, where he lived at the time, and we watched a bunch of his Mexico 8mm films. Great stuff. When we heard he had passed away about 20 years ago we contacted his mom but never got a reply.
Anyway your photo brought back those memories. Keep em coming!!!
Greg
PS I posted a few of my pics, but they were 127 and I could not scan them(no loss as most are crappy by comparison to JBW shots) Thanks!