Appreciate the feedback. I get that the ground or grounds are to be fastened to a grounding source such as the frame. My question is, going back the other direction, where is the ground starting point at fuse block? As I’ve mentioned, I have 1 black ground coming out of the fuse block and eventually makes its way to one of the fans. Are you saying tap this black ground and pigtail off to a grounding point?The double wire ground on the 05+ trucks is a ring terminal attached to the factory side frame rail just above the passenger side frame horn/bumper bracket. It's difficult to see it unless you are specifically looking for it.
I attached mine in the same general area. I grounded it to the bolt that holds the horn to the passenger side frame. And you know that's a good ground because the horn is grounded through that same bolt.