@JPFEIL that is most likely an import vise. Members here on GJ will click on virtually any post that has the word "vise" in it; there are countless experts and interested aficionado's. While there are those who know far than me regarding 1940/50s US made vises, I have a fairly good grasp on most manufacturers and the way in which they were engineered.
The manner in which that particular vise is constructed is not something any US based manufacturer from that era would have used; specifically pinched end handles, very poor casting quality, and "4 1/2" cast in that fashion. The real coup de grace, and its hard to make out because of shadows, but if those pipe jaws are cast onto the dynamic jaw and not removeable, that's another big clue. "About 40 years ago" means the 1980s, or possibly even the 1990s. Very few US based manufacturers of vises were left standing by then.
Any 4-in or bigger vise threaded rod and handle will be heavy, so that is no indication. Also, that logo doesn't ring any bells so far and this post has been viewed by more than 60 members so far. It doesn't look bad and if it works and holds tight, put it to use. Do you have the swivel base that goes with it?