Fulton went out of business in the 1920’s so unless somebody was using their old patterns after that, your vise is at least 100 years old.
Value depends a lot on condition.
As you know, one of the balls that from the handle ends is missing. That’s a big deal for collectors.
If you are able to build a crate for it and get it shipped, go ahead and put it up on eBay and see what the bidding brings. eBay will likely bring the best price.