In regards to the Stag/Stag Ideal, the knife in the middle. The blade was made in 1939 and left in a vat of oil to be assembled at a later time, that's how Webster Marbles did it, made a bunch stored them in a wood barrel soaked in some kind of oil and assembled them as needed. Bob Young, former forman at Marbles was with them for around 35 years he said there were a bunch of these barrels full of blades dating WAY back just waiting to be handled.
But to get back to you're question, yes its pre 01, all of those knived were handled by the custom shop in 99 and 2000. I had a twin to yours and like a dumb azz sold it, but I still have a leather/stag, or 2, in the safe.
DO NOT SELL IT, I see that knife ganing value in years to come. The blade is what everyone wants and the stag is much nicer than what was avaiable in 1930. Keep it, it's a real vintage Gladstone Marbles, the other's are real Gladstone Marbles just not vintage. By vintage I before after the factory re-opened with Lauderman.