Wmart's still sell the Orange stuff (by Prestone) although Ford no longer makes or distributes it (to my knowledge).
Of course someplace has to, as it's still in millions of late model vehicles driving around that could need an emergency top-off or could overheat and possibly die while away from home or an available mechanic qualified to exchange fluids for the newer type.
CarID, Amzon, and most auto parts stores sell the Motorcraft new stuff, in addition to Ford Dealers. There's the prediluted 50/50 (recommended) as well as the full strength concentrate available.
Definitely don't mix yellow/orange as others have said. But get a flush and fill with the new type as soon as practical.
There are also many knock offs or generic "yellow" anti-freeze that say they work with all makes and models or domestic/foreign, etc. They are probably similar base chemistry but wouldn't touch it knowing how bad the wrong stuff can damage your engine. PEAK specifically makes a yellow one that is labeled Ford/Lincoln that might be safe. YMMV, but yellow designed for Ford is probably a lot better off than anything proven to be caustic (orange type).