All Union Pacific for me although only passenger cars. In the UP Excursion line I have gone for (1) add on set #4 which is the one with the Lone Star Business Car and (2) the Promontory “Experience the Union Pacific” former RPO baggage car.
The catalog illustration of the latter car shows it has six wheel trucks:
Please pardon my ignorance but although this strikes me as definitely unusual compared to all of the other Excursion cars offered by Lionel, it seems to be accurate to the prototype, at least judging by the below image:
