We drove US 14 from Cody, thru Greybull, and hit I90 just north of Sheridan. A beautiful fantastic drive!!!!! One of the prettiest routes ever! BUT----it is very crooked and steep in many places. We have a 45-footer with toad and made the trip with no issues. There are not many pull over spots so you don't get many "Kodak moments" in a motorhome.
Take your time and enjoy the drive.