Dave,
20W-H 4001 is your vin number and I believe the second letter is actually "Q" not "O" making your truck a 1947. If I'm right your number breaks down as follows;
2 = Tarrytown, NY Assenbly Plant
QW - 1947 2 ton 161" wheel base
H = August
4001 = Unit number starting with 1001
Hope this helps,
Mike B
