I found the firmware for U.S. Cellular SCH-R890 if anyone needs it. It is from Team US cellulars forums. I re-uploaded it for other people to download if anyone needs it (seeing how it isn't hosted on any of Samsung sites).
https://drive.google.com/file/d/0B-bl5M9mvSUmcno1dE9BcVdpcUk/edit?usp=sharing
https://drive.google.com/file/d/0B-bl5M9mvSUmcno1dE9BcVdpcUk/edit?usp=sharing