Prefer new but used would be okay also. My email is in my profile
I was just looking at Mr. Muffins site and happened to see a Lionel UP engine with flag on it. I think it is what you are looking for.
Lionel 6-85057 - Legacy SD70ACe Diesel Engine "Union Pacific" #8650"
I have a legacy and a Premier one
BMARTZ1991 above would be a very good source! Have purchased from him before, and speak highly of him!