A call to the factory would tell you whether the gun was shipped via Railway Express or some other way. Since we are all human, it may actually be that your gun was somehow missed from making the list that RPM Enterprises is speaking of. Actually, just having the factory tell you it was shipped Railway Express is no guarantee for collectors that it was shipped in a pine box, as RE changed their requirements about this time and Ruger was then able to ship RE in cardboard outer bookwraps as well. Ruger did not list in their shipping records whether a gun was shipped in a pine box or a cardboard box...only the manner in which it was shipped (i.e. Parcel Post, Railway Express, "Yellow" etc.).
Honestly, if you can get $600 cash/trade out of your type 3 Red Eagle, I'd go for it. A 95-98% Type 3 Red Eagle currently comes in at about $400 through the latest price guide that we published in Red Eagle News Exchange.
Chet15