From what I can see it has the roll pins in the slide and I assume that the gun has an internal extractor. If it does even without the proof marks and the date code it is a folded carbon steel slide. The frame and the slide were made in Germany but the gun was assembled in the US. I am going to guess the gun was made sometime after 1996. These are very good guns. They are not as sought after as the German proof guns but they were made the old school way.
Newer Sigs with the milled stainless slide and internal extractors can have extraction issues. The tolerances are too tight. This is one of the reasons they went to an external extractors.
The grips you bought were originally made for the P220 Combat and should fit just fine.
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