This thread has wound around so much, I'm not sure exactly where you are right now. Carolines truck has been steering you into a number of changes, but neglected to correct some of the problems.
The size of wire is very important, but you never, ever use a fuse that is larger than the current carrying capacity of the wire. You posted Amperage ratings of the wire on the other page, but used fuses that were larger.
One example: You have a 20A fuse for the P/windows feeding a 14G wire. You wrote that 14g can handle 15A, but your linked chart says 10A. Either way, the 14G wire will burn up long before the 20A fuse will blow.
There are several other places where you have fuses that are larger than your own wire size/Amperage ratings list agrees with.
I would double check the amperage rating on the wiper/pump. The only reason I ask this is the original on my '67 is 20A.
The constant supply for the stereo to keep the clock and pre-sets would be measured in milli-Amps. 10A is a little over kill. Here is an example of a case where you can always use a fuse size well under the rating of the wire size. 3A or smaller would be my choice.
There are still others. 20A feeding 14g wire for brake light. This is an AD truck. Are you planning on running that many lights in the back. I'm just surprised you didn't combine the brake and turn signal.
I really don't see the need for two distribution blocks. I personally would have used only the one on the firewall. That would allow you to run a shorter 8G wire right across the firewall. If you still wanted a block towards the front for the fan and head light relays fed by a 10G that would be fine. The Gen and Gen sensing wire would go to the firewall block. The Gen sensing wire should see all of the battery load. Your setup has the fan and light load before the sensing wire.
The Gen exciter wire is another other area that could stand some changes. Gm always placed a 10 ohm resister in the harness, in parallel with the Gen light. The resister allows the exciter circuit to function if the light should burn out. This line should not have any accessories on it. The tach uses little power and can be fed from most anything going to the dash. The volt meter won't hurt anything, but I would hook it directly to the fuse block feed. Now for the fuse. On this, I would agree with Automarc about possibly having too many fuses and fuse links, etc.. Copper wire has resistance and so do connectors, plugs, crimp connectors, fuses and fuse links. Every time you add anything to a line, you are adding resistance as well as locations for corrosion to occur.
You have the power seats on "constant power". The reason I question this is because in my Vette, the switches tend to get dirt in them and stick in the on position and run the battery down. Where they are located, passengers sometimes lean on them getting out. Just a thought.
The P/windows on the other hand may end up needing to be wired hot because that alarm setup you are showing will probably have the capability of running the windows up for you, when it locks the doors.
