Recipe I got from the head of our machine shop at work, I normally make this every year around the holidays for family gatherings and there are rarely ever any leftovers. Excuse the all caps yelling below, i copied and pasted the recipe from an email the older gent that recently retired sent me. 
SEAFOOD CHOWDER SERVES 12 TO 14
3-4 – 18OZ. CANS OF NEW ENGLAND CLAM CHOWDER (PROGRESSO, DO NOT ADD WATER)
2-3 - 12oz. BAGS COOKED CLEANED FROZEN 41-60 COUNT SHRIMP WALMART (THAW AND PULL OFF TAILS)
1 OR 2- 1LB. OF RAW SCALLOPS FRESH OR FROZEN (THAW, DRAIN, IF LARGE CUT INTO QUARTERS. SAUTE SCALLOPS IN BUTTER JUST UNTIL DONE (DO NOT BROWN) ADD TO SOUP POT SCALLOPS AND SAUTE LIQUID
1LB. BAG OF FROZEN BLACK SHELL MUSSELS FULLY COOKED, THAW AND ADD TO POT LEAVE IN THE SHELL
A CAN OF CRAB MEAT CAN BE ADDED BUT IT WILL PRETTY MUCH DISAPPEAR WITH ALL THE OTHER INGREDIENTS. OR YOU CAN ADD A PACKAGE OF CRAWFISH TAILS
1- 1LB. PACKAGE OF SEA STICKS IMITATION CRAB MEAT (CUT INTO SMALL PIECES)
1 QUART OF HALF AND HALF
1 15OZ. JAR OF CHEESE WHIZ (WARM IN MICRO WAVE)
1 TO 2 TABLE SPOONS OF OLD BAY TO TASTE
FRESH GROUND BLACK PEPPER (LOTS)
ADD ALL INGREDIENTS TO SOUP POT HEAT ON LOW KEEP STIRRING TO AVOID SCORCHING THE CREAM BASE
COOK ON STOVE TOP IN LARGE STOCK POT OR IN CROCK POT
SERVE WITH OYSTER CRACKERS
SEAFOOD CHOWDER SERVES 12 TO 14
3-4 – 18OZ. CANS OF NEW ENGLAND CLAM CHOWDER (PROGRESSO, DO NOT ADD WATER)
2-3 - 12oz. BAGS COOKED CLEANED FROZEN 41-60 COUNT SHRIMP WALMART (THAW AND PULL OFF TAILS)
1 OR 2- 1LB. OF RAW SCALLOPS FRESH OR FROZEN (THAW, DRAIN, IF LARGE CUT INTO QUARTERS. SAUTE SCALLOPS IN BUTTER JUST UNTIL DONE (DO NOT BROWN) ADD TO SOUP POT SCALLOPS AND SAUTE LIQUID
1LB. BAG OF FROZEN BLACK SHELL MUSSELS FULLY COOKED, THAW AND ADD TO POT LEAVE IN THE SHELL
A CAN OF CRAB MEAT CAN BE ADDED BUT IT WILL PRETTY MUCH DISAPPEAR WITH ALL THE OTHER INGREDIENTS. OR YOU CAN ADD A PACKAGE OF CRAWFISH TAILS
1- 1LB. PACKAGE OF SEA STICKS IMITATION CRAB MEAT (CUT INTO SMALL PIECES)
1 QUART OF HALF AND HALF
1 15OZ. JAR OF CHEESE WHIZ (WARM IN MICRO WAVE)
1 TO 2 TABLE SPOONS OF OLD BAY TO TASTE
FRESH GROUND BLACK PEPPER (LOTS)
ADD ALL INGREDIENTS TO SOUP POT HEAT ON LOW KEEP STIRRING TO AVOID SCORCHING THE CREAM BASE
COOK ON STOVE TOP IN LARGE STOCK POT OR IN CROCK POT
SERVE WITH OYSTER CRACKERS