All of the Colt replicas were licensed by colt, and made from Italian parts. The Italians kept the old guns alive because of the spaghetti Westerns, and to this day shooting old replicas of American guns is a passion with them, probably more so than it is in America today. On several models the parts are completely interchangeable with the originals. Which I think is the case with the 1860 Army. You could put Uberti parts on an original and vise versa.
The only difference is the modern replicas have better metallurgy. That's important, the modern Walkers can actually hold their charge without going boom.
If you want a Walker then the only practical option is the Italians. There were only 1100 Walkers made, and a third of those blew up because of their metallurgy. The price for an original Walker is approaching a million dollars. However, you can still get an original 1860 Army, if you want to pay a couple of thousand. There were also a lot of Dragoons made, but they'll run you more. I can't imagine shooting either of those on the regular, but I guess you could if you had your heart set on a made-in-America example.
Personally, I'd just get an Uberti and enjoy shooting it. It's never going to be a collectable in our lifetime. The price of admission is reasonable, and the quality is great. At least as good as the originals with better metallurgy. You can pay a little and get a gunsmith to slick one up for you, and you're good to go.
If you want one of the replicas licensed by Colt here you go...
http://www.collectorsfirearms.com/colt-modern-blackpowder-replicas/
Here's the story on the Colt signature series....
https://www.americanrifleman.org/articles/2014/6/18/i-have-this-old-gun-colt-3rd-generation-signature-series-1851-navy/
They're Uberti parts, stamped Colt, and assembled at the Hartford plant, that will run you over twice the price of just buying an Uberti. But they
were assembled in America by Colt.