OEM Rear DVD

[Nerk]

Question I can't figure out, hoping somebody knows:

I have an '08 Tahoe 3LT with nav, but no rear dvd. If I purchase a nav/dvd unit and the rear overhead monitor, will the wiring for the rear overhead monitor be there under the headliner, or will I have to get a harness?

If I have to get a harness, does anybody know what harness it is?

 

[Andy4639]

I bought a drop down dvd for a golf cart. It only needed a hot & ground wire that would connect to the over head light and it worked through the radio with the cordless headsets too. I got it off E-Bay.