The bypass elbow leak that you're referring to is a common issue on the 95-99 Series II 3800s. More often that not they will develop a small crack. If the upper intake manifold, upper intake gasket and lower gaskets have never been replaced you should consider doing it as soon as possible. Even if there is no coolant consumption, it will inevitably happen in the future. By doing it now, you'll save yourself from a hydrolock. You should also consider doing a full coolant system flush and replacing the OEM 195 degree thermostat for a 180 degree. The bypass elbow is most easily replaceable by removing the lower intake. The new elbow costs about $7.00 US from the dealer.