leadlum,
The slide on a S&W 1911 with adjustable sights has a different machine cut than the fixed sight model. although the dovetail is probably the same the adjustable sight slide cut is further foward to accommodate the longer sight body. The rear of the adjustable sight slide is also cut out for the rear of the sight. The fixed sight slide does not have this cut.
Also, the front sight of the adjustable sight slide uses a higher front sight.
Best,
TnNuc