I just purchased a used Leaonard brand shell for my 2005 HD. I would like to wire up the third brake light (same power also feeds an interior light in the shell) but Im not sure what wires to tap for this. I think that the tailight wiring is used.... but again, I'm not sure. Can someone help me? Also, what type of connection (fpr quick disconnect for removing the shell) is between the wirng to the tali lights and the wiring to the third brake light on the shell.

Thanks in advance for any help!