I have a 70 boss and was missing the orig. rear spoiler. I now have one to put on my car but was wondering about the reinforcement brackets that go on the inside of the decklid (underside). Were they used for all 69 and 70 mustangs with spoiler or was it based on plant or implemented in a certain month? Don't want to find and add them if they weren't correct for my car. Thanks in advance for your thoughts.