Shoulder insignia indicates a Technician 5th Grade (T/5) with the US 5th Armored Division.

For whatever reason, this artwork apparently comes with a Korean War boxing of AFV Club's Chaffee kit, despite the Technician ranks being deleted in 1948 and the paint scheme here not matching the kit decals. They haven't released the WWII boxing yet, though, so it may ultimately be destined for that.

Edit: There's another one of these pictures for their NM116 ('70s Norwegian M24 upgrade) kit, though I can't find it right now for the life of me.

AFV CLUB is actually a plastic model manufacturer if people want to know.