Replaced started and battery cable arcs and blew a fuse

[Funstuie]

Hey all

My never-ending search to fix my electrical problems have created another issue.

The battery died and I also messed up the alternator and or starter. So I figured I would just replace all components. I got like for like replacements and just wired everything up as it was before. When I went to put the new battery in the positive wire arc'd and blew a super fuse.

I decided to trace the wires from the starter (this truck has lots of extra wires added over the years).

There is an ignition wire which is fine. There is the direct battery wire and another wire which I traced to a distribution block on the firewall, from that distribution the wires are connected together and I have traced the wires to the alternator (there was also an extra wire to nothing on the distribution block which I removed).

So is this (attached pic) correct? And what could cause the positive wire to arc with the new starter?