2009 Denali. Front driver side of engine bay, there is an empty spot, looks like a second battery tray. Behind that (closer to firewall) is the main fuse box. Remove the cover and there are two screw posts, both are hot. One is thicker and silver, the other is thinner and painted over it would appear. Can I use the thicker silver one to mount my 4 gauge amp power wire too? I was thinking it was a terminal to attach your second battery, but I want to be sure. Now going inside. I am running a LOC because I am keeping factory HU. Where is the best place to tie in the LOC? Please help if possible. I've been searching the archives and can't find answers to these questions.