Uniden pc68xl /cobra 25ltd DIRECT AUDIO INJECTION POINT?

I I am trying to set up audio direct injection on both of these radios and all I'm finding on the Internet is information on the cobra 29 The 29 board and these boards look similar but I don't understand the process enough to understand to figure out where to inject on either one of these radios. if someone could help, point out how it works and where it's actually entering at and any other information that would be great.
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Uniden pc68xl /cobra 25ltd DIRECT AUDIO INJECTION POINT?