On the BNSF tracks a few miles S.W. of the Argentine yard, I saw one engine pulling a couple of FRA cars. That was the entire train. On car looked like a support car and the second car (end of the train) was definitely an observation car of some type. It had large windshield type windows on each end, kind of like an old city bus or similar. It was clearly marked Federal Railroad Administration and Office of Safety (or close to that anyway). It was pretty cool to see! I had never seen one of these before. Sadly, it got past me before I could get a picture of it. I did find a couple of pictures on the internet, posted below. I didn't get the car number, but it looked exactly like the pictures below.
