Note: groups.io will be down for maintenance on Wednesday, October 5th, starting at 9AM Pacific Time (4PM Wednesday October 5, 2022 UTC), for approximately one hour.
Wow. Not a ladder in sight, going up to the domes.
The car on the left (I'm assuming UTLX 639 or 629) has a curious mid-car tank hold-down rig, that goes around the dome. And a railing, instead of a handrail, along the tank. I see at least two similar cars on the other track, and it appears they also have the goofy mid-car hold-down.
In 1926, there were 190 cars in the series 551-999.