aftermarket camera to oem navigation
 

Hello everyone, I am new here I had a hard time just trying to post this message. I have a toyota 4runner SR5 I have a toyota TNS510 navigation head unit. I dont know if this unit is available in the united states I got it from a canada seller on ebay, anyway my question is that I have an aftermarket backup camera already installed on the truck and I would like to know if there is an adapter I can use to connect that camera to the navigation unit or if I can tap into one of the connectors behind the unit to connect the camera.
Thanks for your help.

Also I forgot to mention that my 4runner is a 2007 and is non jbl. if anyone.can help me on this I will really appreciate it. Thanks