You can probably add $100 or so to that 1990 figure, but the condition keeps the gun in the low price range. (It also appears to have been polished and cold blued, which would lessen the value more than if it had been left alone.)
When Colt made those guns for the civilian market, they kept pace with the military production in regard to changes and updates, but never gave them new model names or numbers. The civilian production guns were called the "New Army" and the "New Navy" but at any given time they were identical except for the grip design, in this case the "New Navy."
Those guns by that time had barrels sized to the .357" bullet of the .38 Special and can fire that cartridge with good accuracy. Note, though, that only standard velocity .38 Special should be fired in that gun; no +P and definitely no +P+. The chambers are bored straight through and even .357 Magnum can be chambered, but certainly should not be fired.
The barrel marking was not changed, at least in part because the .38 Special was properly called the ".38 Smith & Wesson Special and there is no way Colt would put that on their guns.