In a medium bowl, beat cream cheese with an electric mixer on medium speed until smooth. Beat in mayonnaise, mustard, and salt. Stir in crabmeat, green onion, and red pepper until combined.
Butterfly each shrimp by cutting through the rounded side almost to the other side. Open shrimp and lay flat, cut side down, in prepared baking pan. Divide crab mixture among shrimp, shaping the mixture into a mound. Bring shrimp tails up and over the crab mixture.
Bake about 10 minutes or until shrimp are opaque. Serve warm.