Salad:

1 (7 oz.) pkg. macaroni shells
1 (16 oz.) can peas, drained
1 (4 1/2 oz.) can shrimp, rinsed and drained
1 (2 1/2 oz.) jar sliced mushrooms, drained
1 c. chopped celery
2 tbsp. diced pimento

Cook macaroni. Rinse and drain. Combine with remaining ingredients in large bowl. Gently stir in dressing. Cover and chill at least 2 hours before serving.

Dressing:

1/4 c. milk
1 1/3 c. mayonnaise
1/2 c. cocktail sauce
1/2 tsp. salt
1/4 tsp. pepper
1/4 tsp. onion salt
1/8 tsp. celery salt

Combine milk and mayonnaise until smooth. Add remaining ingredients and stir well.