I did the same thing I had done with the questionable 1958 Aaron a while back and upped the saturation and what not in photoshop. With this card (assuming the photo wasn't doctored by the seller before being uploaded to ebay), you can see the yellow only appears within the delineated area of his name. This isn't an exact science or anything, but this result probably points to the card being authentic. Of course, if it was doctored, then he/she could have possibly used a very thin yellow pen/marker to color the name in without ever drifting into the red area (which was ridiculously obvious in the Aaron card mentioned above). That is possible, but not very likely.
I would say it is, in fact, a yellow letter card.
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