1. Cook shells according to package directions until tender but still firm; drain. Rinse under cold running water; drain again. 2. Invert shells on paper towel-lined plate to drain and cool. 3. Drain and discard liquid from crabmeat. Place crabmeat in large bowl; flake with fork into small pieces. Remove any bits of shell or cartilage. 4. Add remaining ingredients to crabmeat. If mixture seems too dry, add more mayonnaise. 5. Using large spoon, stuff cooled shells with seafood mixture. Cover; refrigerate until chilled.
