Battery to power distribution voltage drop issue

[texas_snake]

I have been working out the kinks on my 03 Mach 1 since buying a couple months back. Been chasing a voltage issue many accessories are running (lights and A/C mostly). I noticed over time the positive battery to power distro box is heating up and having voltage drop over time when running with the extra's on. Over time drop can be big (.75 volts or more) so I am checking into cleaning main grounds.

But one thing has stood out. The yellow positive connection is on my positive battery post. Looking at stock mach 1 engine pics, it looks to connect to the power distro block along with a smaller connection off the positive battery cable. So the question is, do I have to have 2 connections on the power distro box (yellow from harness and red from positive battery) and just one going to the positive battery? It is 1 red to power distro box and 2 - yellow and red to the positive battery now.

I have suspected this for a while, but now that I see voltage drop there with heating when loading the system, I really need to know if this matters or not.

I would switch it, but the power distro box threads are messed up and that nut wont come off easily and I don't want to damage the fuse box, but will give it a try to move it if that is required.

Thanks!