Capo:
According to JD's latest book, there were only 1,046 pine salt cod type boxes built for Ruger for one Ruger .22 pistol and an additional 202 pine salt-cod type boxes built for a two-gun package.
My notes show verified salt cod guns as existing from two-digit serial numbered examples all the way up to 5009 which is the highest gun I know of with certainty was shipped originally in a salt cod box, a gun that was shipped in May 1950. A couple higher serial numbered guns are known that are currently in salt cod boxes, but those two do not appear in the list that JD published, so we can only surmise that those two may have been sent back to the factory for some type of repair and then returned to the owner via railway express in the pine box.
It is really hit or miss with a salt cod boxed gun (when it doesn't have the pine with it) as only about 10% of the guns up to your serial number were ever shipped in one to begin with. And to be honest, I'm not sure all those higher numbered guns in JD's list up to the 9xxx were shipped in pine as Railway Express eliminated the need to ship in wood boxes sometime in the early to mid-1950's.
I've also seen a few .22 pistols in wood boxes, but nothing like the ones Ruger shipped their early guns in.
Chet15
Another note: Ruger didn't see the need to have any pine boxes produced for their Mark I auto first shipped in about January 1951. Of course, Ruger's distributor system had been developed by that time so the group lots were going out with cardboard sleeves or even cardboard cases via yellow carrier or something of the sort. This is what leads me to believe that in 1950 or 1951 RE changed their policy of the need to ship in wood boxes. There are also a couple of RE shipped flattops known that have cardboard sleeves.