Like Stainz says, that one doesn't have the interchangeable front sight. It might not even be a 163638. Since you have the box, assuming it's original to the gun, what is the Product Code on the label? While you're at it, what is the Spec. Ord. number? A picture of the label would work best.
Yep, it's a product code 163698. That's actually a pc I've never seen before. In general, the gun looks standard, accept for the Hi-Vis front sight and V-notch rear blade.Yup, the label has a different Product Number.....