Columbus Day UFO special

[Forgotten Field]

Columbus Day! I can't believe they give kids the day off for a bunch of Syphilis-ridden spaniards who didn't even make it to our shores, mutinied because they ran out of cabin boys, and had trouble finding their way home...

Anyhow, here it is. I believe it is some type of down lock/mount for Grumman landing gear. It is USN, but don't have the numbers.