Thanks, that is in fact the only "serial" number on it. I haven't seen it, he sent me a pic but it didn't come out so I asked for another.
Edit: Here are the pics he sent me. The same number appears in both places and there is no number on the bottom of the grip.
When Don mentioned there was no s/n on the grip butt, it would have been good if we had caught that and put up a red flag. I tried to copy the photo from the post on the 1st page of this thread, but it didn't follow. Since the gun in question is a 10-5, and most likely a square butt, a close look at the frame in question makes it appear this was a conversion, and in the process the s/n was removed. While I can certainly see the desire for a butt conversion, there isn't a reason to have to obliterate the whole serial number in doing so.
Guns without serial numbers or altered ones carry a harsh penalty to the Owner/possessor, not necessarily just to the person who did it - this is how the BATF enforces the law. If you run across this, do not purchase the gun, and be a good citizen and let the owner know of the risk they are taking. I would not run to the law, since mostly it's some innocent guy who doesn't know that is in the spot, not a gangster. Should the gun be used in even a lawful self-defense situation, serious jail time could follow when the gun is examined in police custody.
I painfully walked away from a great deal on a completely intact WWI 1911 last year at a gun show - when examining it I realized the "US Property" had been skillfully removed, along with the original Colt s/n, and another one in different script substituted. As much as I likely would have had no problem, it just wasn't worth jail time.