To me, your Wilton date code looks like "4 83" stamped twice, alternated upside down.
I've only seen one other alternating upside down Wilton date code, but it had different year stamps.
Can you post some photos of your vise, including the side view that shows the casting numbers. I suspect the number might be a little different than the "101152" that you indicated earlier, possibly a "101162". I'm guessing that your Wilton bullet vise has 4-1/2" wide jaws.
Either way, it's an interesting date-code discrepancy that is rarely seen.