UP Business Train?

On Tues. afternoon, 10/7, while driving to Salt Lake City w/b on I-80, I saw what looked like a UP "passenger train" with one engine heading up 6-8 cars in UP livery. This was where the tracks are just north of the interstate around the Nebraska/Wyoming border.

Some of the cars looked to be sleepers/observation cars/business cars. Was this possibly a business train move heading to Cheyenne, Wyoming? Nice sight, anyway, on a beautiful day. Sorry I couldn't get any pictures.

Do you know what engine? Because the UP Steam Shop is in Cheyenne, also home to the last operational Centennial and UP E units.

I'm not an engine maven, able to spout off manufacturers and model nos. like some. Only thing I know for sure is that it was a contemporary diesel engine, not one of the steam jobs. If it were that, I would have pulled over somewhere and definitely got some pix!

Well it probably was headed towards Cheyenne because that is where it is ussually kept, with all of the other old equipment.