26XXX was made in 1963.
The year started at 24800 and ended at 30799.
This qualifies as a genuine "early" Python, and prices on the earlier guns are higher EXCEPT if re-blued.
ID-ing a re-blue can be tough, especially if Colt did it.
It's not unusual to see light stamps on some guns, so that "might" not be a good indication of a re-blue.
Take a look at the other stamps and check for slight raised "ridges" around the markings.
When a gun is roll-marked, the pressure of the die forces metal up around the marks, leaving a slightly raised border around it.
Polishing during a re-blue polishes the ridges off, leaving the mark smoother.
An early 60's Python will have the old, higher polished blue job. This was the finest bluing ever done on a production firearm.
This looks totally different than other bluing, and can be recognized by a brilliant mirror-like deep BLUE color.
It's MUCH shinier than other bluing, and when clean glitters like a blue mirror.
Sharp edges and corners will be sharp, and all flats will show NO waves or ripples.
With all that said, Colt has quietly said that the Colt double action revolver is no more.
They have permanently discontinued the Anaconda and Python and have no plans to make DA revolvers again, certainly NOT the Python.
The news of this has hit, and Pythons at gun shows that WERE tagged at $800 to $1000, are now tagged at $1400 AND UP......... and are SELLING at those prices.
Personally, considering that this is probably a re-blue, based on the nice appearance and the fact that it was a duty gun, I'd offer $600 to $800.
This is based on actual condition, AND on whether it's in proper time and adjustment.
Even an early Python's value is pretty well reduced to "ordinary Python" by a re-blue.
If you ever want a Python, this might be a good way to get an early model with it's better fit and finish, even if it has been re-blued, as long as the re-blue is a quality job.