Yes they did. I saw it at the last gunshow. The only one ever made.
A fellow came by our table, he and I engaged in friendly conversation. He was nicely dressed and appeared "normal".
Then he told me how Colt had made a stainless gun well before anybody knew stainless guns were actually made.
Then he pulled out the gun only and showed it to me.
It looked just like this one.
Then he told me it was made as an experimental in 1898 by Colt to test the ability to make a gun in stainless.
I asked him if it was a Colt 2nd Generation. He said no. Unfortunately for me he was not wanting to sell it, he was only showing it off. I'm sure his "1898 Colt stainless 1860".................IS WORTH A LOT!!
He WAS serious.