obd2 magnum swap?

I figured out the belt. I took of the idler pulley and using the truck non ac belt it fits. I started looking at the wiring and apparently I'm missing C3 on the ecm and I have the wrong fuse box. Now I'm scratching my head as to what to do. I don't hang to spend $900 on a hot wire harness. I'm usually good at wiring ford's I'm just not familiar with dodge wiring diagrams so it's hard for me to decipher how stuff works and their terminology.