Flea Market Find, What Is It??

I was at the flea market and found this for only $10 and I have no idea what it is. It's pretty heavy and the base dimensions are approx 8" by 4.5", the top turns 360 degrees and the dovetails are scraped. The shaft with the pully on it flips up and out of the way. The only markings are 4683 and No 3. Any ideas.

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