Detroit Diesel 8V-53 exhaust outlets ???

Questions please: My year 1972 Chris-Craft 47' Commander with the original twin Detroit Diesel 8V-53 engines have the standard placed wet exhaust outlets on each stern bottom side, however, these original Detroit Diesel 8V-53 engines also each have an additional wet exhaust outlet to the side of each engine above the waterline under the quarterfoil and my questions are: 1. What is the purpose of these additional wet exhaust outlets on each side of the original Detroit Diesel 8V-53 engines ??? 2. Are there additional thermostats within these additional wet exhaust outlets' systems on each side of the original Detroit Diesel 8V-53 engines ??? 3. Has anyone seen these additional wet exhaust outlets' systems on other years of the Chris-Craft 47' Commanders or the 55' Commanders or the 60' Commanders ??? 4. Do you also own this additional wet exhaust outlets' systems set up on your Chris-Craft 47' Commander ??? "Thank You", in advance, for your information and time. Kind Regards, Mark Patrick Hillman