[mongocanfly]

That big red wire that connects from the big starter lug to the junction box on firewall is what carries power to the trucks original electrical system so yes you need that. From there it goes to your fuse panel.For the alternator wire I simply ran a heavy wire from my alternator lug to this same firewall junction. No need to tie it into the red box on your battery cable. It will feed back to the battery from there. And yes the big pink wire that goes to the old distributor is used as your switch on power.you can check that with a volt meter if you are unsure. It will show 12v when switch is on and 0v when switch is off if you have power to that firewall junction box. That is what i used power all my switch on power needs. I ran it back into the cab and hooked it to a junction strip and then connected everything to it under the dash...makes my head hurt trying to remember this stuff...