I was just reading in an early service manual that I have, and it agrees with that. It states that production started in April of 1947. Clearly Herb's book is wrong, whether it was an oversight, or just a typo, I don't know. I wish I had taken the time to confirm what is in his book. Hindsight is always 20-20.

Thanks for the info. I should have checked Culbertson's book as well. Let this be a lesson to not get in a hurry, and always to verify sources, even when I think they should be right.