The 2 part numbers you gave above are just gaskets. They didn't replace the actual UIM (Upper Intake Manifold), just the UIM gasket. On pre-99 Vin-K 3800's, the UIM is the most common failure part that causes internal coolant loss. An inspection of the coolant passages around the EGR stovepipe, looking for erosion (they will look pitted and rough instead of smooth) as well as deformation of the surface of the UIM, should have been done instead of just replacing the gaskets. On Late-99 and newer 3800's after the GM UIM revison, the gasket was the weak link. However, if let go long enough with a bad gasket, the resultant coolant leak will erode the UIM even on the newer design, requiring UIM replacement as well. The only way to know for sure is with a thorough inspection.