Not 100% on this one, but I think it might be authentic.
Actually my first thought was fake.
But when taking a closer look it does look like his handwriting. For example compare it to this index card.
http://www.autographworld.com/theme/sho ... p?item=382
See how the F in From is formed a certain way, same with the TH at the end of Meredith.
Another example you can find here.
http://img.photobucket.com/albums/v636/ ... urgess.jpg
It's a pretty good match. Especially if this was received a short time before he died, the shaky handwriting makes sense. He was almost 90 years old when he died.