Which interface module for '07 LTZ ?

I was told to get this: http://www.discountcarstereo.com/RP5-GM31.html  (not AT that site in particular, but that unit)

But then read the stuff in red letters.

My head unit is a Kenwood DNX-6990HD.  Is that the interface module I need?

need more information on your truck ....

you might want to check out the interfaces here ... www.pac-audio.com

John