I need some advice on wiring a new radio - The USA-740

The previous owner had run a red fused wire right off the accesory fuse panel and a black wire off the drivers side courtesy light bracket to power the old radio. I pulled those off to clean it up a little and tried to wire up the new radio which just requires a red switched on wire and a yellow constant wire, plus ground.

Problem I've ran into is the previous owner also wired an aftermarket gauge cluster and I can't make heads or...

What wires for USA-740 aftermarket radio?