My 1998 LeSabre with 30,000 miles on it developed an external engine coolant leak in way of the EGR pipe. I had the upper plastic intake manifold and the lower aluminum intake manifold plus all gaskets changed at an independent shop. Thanks to this list I knew enough to insist that the aluminum manifold be replaced and to make sure that the new aluminum manifold - GM part #24508923 - had a smaller diameter EGR pipe than the original. Thanks Ian!
The replacements parts totaled: $621 excluding tax, and the labor totaled: $216.
John