Yeah on my truck I have ground wires to engine, chassis, body and well back as you can't have to many earths around the truck but have you tested the starter wire from the ignition to starter when key on for starting.
I haven't specifically tested it yet, but I don't think I'm getting anything from ignition to starter as I think the issue is before that point. I'm not getting power anywhere, so it's broader than just the starter. I have power at the starter, the voltage regulator, and at the connections that I can get to in the engine compartment. All I can figure is that something came loose or shorted when I either pulled the connection from the old battery or reattached it to the new one.
Yeah, I'm getting power at the white and green clips in that picture, which are downstream from those links, so don't think it's that. I haven't had a chance to do any more digging over the last few days, but will be back at it again tomorrow. I'll double check those links as they look like a potential fail spot.
You were right, @lostmarbles, there's an issue with the wire that has the yellow link. I could have sworn that I tested each of the connections on the downstream harness, but must have missed one as I retested this afternoon and wasn't hot on one connection. Did some additional checking and the wire between the connecter and the green harness was limp. I barely moved it and the sleeve came off. There's now a questionable piece of wire coming out of the one harness and a clean one coming out of the other harness (see pics). Is there a way to get wires out of these types of harnesses? If not, does it make the most sense to replace the harnesses? Lastly, does anyone know what gauge of wire I'd use to replace the bad section? Thanks again for all of the help.
Those are your fusible links. They protect the wires in your harness. They do this because they are of smaller-gauge wire and will melt/blow (as that one has) before the thicker harness/loom wires will.
Yes. They are easy to repair - Just use new spade terminals and run a new length of wire (same gauge and length as the original) between them..
Search and you should be able to find how this is done.
PS. Does your ammeter work? Depending on which fusible link this is, it's failure may have automatically caused one of your ammeter fuses to blow at the same time.