Just to add...
I believe this was a standard offering by Wilton, or perhaps in a special-purpose catalog. I have one just like the one originally posted. Same thing--casting numbers align with the 744. It uses a steel washer-shaped thrust collar held on with two screws (which I don't see with the same configuration on newer versions) that is held in place on the main screw using a snap ring.
Another similarity is that instead of swivel handles, the swivel lock bolts have nuts on them. If there was just one that way, we'd be confident they had been replaced at some point. But with two, it opens the possibility that they were supplied in that configuration. I've ordered swivel handles for mine--keeping the wrench handy is a pain and I use the swivel of my vises frequently.
Also, both mine and the one pictured by the OP are not equipped with pipe jaws, and in my case, the screw holes that would keep the jaws in place are not present. Were I to install pipe jaws, I'd have to drill and tap the castings.
But the key thing is the spacing of the holes for the replaceable jaws. The holes are not spaced at 2-1/2" the way that 4" jaws are spaced, but rather at maybe 1-3/4" (I can get precise measurements if anyone is interested). The screws are the same narrow-head 1/4"-20 that they all use, and I was able to find some narrow filister-head screws at McMaster that work perfectly. (My vise was missing two of the screws.) That tells me that Wilton made this vise with 3" jaws on purpose. Fortunately, the jaws on mine are perfect.
In my case, the vise was mounted on a MB Century work cart (Metal Box and Cabinet Corp of Chicago--who made Snap-On boxes in the day) that was labeled "Elevator Shop" in painted stencil letters on the side. Both were painted the same color that I call Janitorial And Building Maintenance Office Gray. The cabinet itself is very beefy and solid, and has a roll-down cover for the drawers. It sits on casters with 4" wheels, and has Colton corner bumpers all around. Finally, it has a 120-V receptacle that is fed by a recessed male NEMA 15-3 receptacle into which any extension cord can be plugged. It was dirty as hell when I got it--I didn't find rodent parts in it but I was surprised not to. Bought it from a local guy in Virginia for less than either the cart or the vise would be worth separately, so I'm pleased. It was the cart I was after--the vise was a bonus. It's a far better vise than the sloppy 90's-era 6" "Wilton" homeowner vise I bought a couple of decades ago (that has "Columbian" and "Made in USA" cast into it).
I'm prepared to believe without further evidence that these were special versions sold in catalogs marketed to building maintenance professionals and the like, at a slightly reduced price to account for the missing pipe jaws and chrome-plated swivel handles.
Rick "outfitting a new shop with old stuff" Denney