The Walker is an older Uberti I think, no bbl address nor frame markings that I can find. The 1851 Squareback Navy is a 2nd Gen Colt that I picked up for a song, this because the previous owner had 'aged' the pistol. Both the Walker and the Navy have bery nice actions and timing.
edit: there is a PN on the right side of the bbl/ wedge area, upper left hand corner.