Nice that they're still supporting it. Wow.
On your red & black wire pigtail, when you hook it back up.... that post on the ACC terminal in the fuse box is a great place to get switched 12V + power. Go back there. The post right below it is an ACC ground. You can either run the black wire to that, or run the black wire to battery ground like the installer had it. Whatever is easier. There are other grounds, but probably easiest to stick with where you've been or we're you're going anyway.
This is my signature block. There are many like it, but this one is mine.
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