Very little of Willow Run is left. Most of the assembly area, as well as the office building, has been demolished. The Yankee Air Museum is working to save the hanger area as well as some of the adjacent space. I visited there about two years ago and a sympathetic guard let me wander some of the complex but there wasn't much to see but rubble. I gathered several bricks from a few different spots on site as I was leaving.
In Toledo, all that's left is the Overland smokestack. The main office building, assembly buildings, as well as a Willys era engineering building that was later home to the Jeep House Museum, have all been demolished. I was lucky enough to be in Toledo when the assembly building came down and was able to gather a few bricks from there as well.
For those visiting both areas, there's little to tell of KFs presence.