I'm going to be installing an aftermarket head unit in my 2011 Tahoe and was told by someone who I work with(who used to install audio equipment) that https://www.sonicelectronix.com/item_19628_PAC-Amplifier-Integration-Interface-for-Select-GM-Vehicles-AOEM-GM1416.html would work for installing the head unit. On doing some more research I see that this is for adding a amp to the truck.

Can someone help clarify this for me. I've already got the head unit and the harness should be here tomorrow. Should I just send it back before opening it and buy a different harness?