Factory ammeter
Those are one thing to look for and IF one of them has wires that are 12 gage or larger, that might be a grommed used for the battery feed.
If they look just like the ones on his car, (wire colors, size, and location) then its probably the same as his car.
Below is a stripped down wiring diagram of a standard option power scheme (up to '75/76).
Use it while looking at your car.
Begin with the battery positive. At minimum there will be one very large wire to the starter, and 10 ga wire to the starter relay.
If you find other wires, note that down. For example some cars have power for hazzards wired in at the battery.
From the starter relay to the firewall the battery feed should connect into a fusible link. Then the link into either a wire or connection at the firewall.
The battery and alternator power connections at the bulkhead connector were usually sealed.
Now if the harness wrap is still on the wires its more difficult to follow the wire. Knowing where to look for it to show up helps.
You can see a nice example in this photo of the firewall of @zkx14 Duster.
The white arrow indicates the flag on the fusible link.
Something else you can do to follow a wire is to use an ohmeter or powered test light to see if the wire ends you are looking at are connected.
To do this:
Disconnect the battery. I generally remove the ground connection first, then the positive.
Then connect the meter to the disconneted battery positive clamp. Touch the other probe to whatever wire end or terminal you are looking at.
If there is no resistance or the light turns (or beeps) then you know the ends of the unknown wire are connected.
The alternator output is more difficult to follow because in a standard wiring it goes direct to the firewirewall connector, then to a welded splice where it conencts with the other feeds. That's all sealed except on the inside of the bulkhead connector.
As you might infer from @zkx14 in that post, those type of wire grommet feed throughs were used for many purposes.
Those are one thing to look for and IF one of them has wires that are 12 gage or larger, that might be a grommed used for the battery feed.
If they look just like the ones on his car, (wire colors, size, and location) then its probably the same as his car.
Another thing you can do, and I think it would be good to do just to learn your car's wiring better, is follow the power feeds.
Below is a stripped down wiring diagram of a standard option power scheme (up to '75/76).
Use it while looking at your car.
Begin with the battery positive. At minimum there will be one very large wire to the starter, and 10 ga wire to the starter relay.
If you find other wires, note that down. For example some cars have power for hazzards wired in at the battery.
From the starter relay to the firewall the battery feed should connect into a fusible link. Then the link into either a wire or connection at the firewall.
The battery and alternator power connections at the bulkhead connector were usually sealed.
Now if the harness wrap is still on the wires its more difficult to follow the wire. Knowing where to look for it to show up helps.
You can see a nice example in this photo of the firewall of @zkx14 Duster.
The white arrow indicates the flag on the fusible link.
Something else you can do to follow a wire is to use an ohmeter or powered test light to see if the wire ends you are looking at are connected.
To do this:
Disconnect the battery. I generally remove the ground connection first, then the positive.
Then connect the meter to the disconneted battery positive clamp. Touch the other probe to whatever wire end or terminal you are looking at.
If there is no resistance or the light turns (or beeps) then you know the ends of the unknown wire are connected.
The alternator output is more difficult to follow because in a standard wiring it goes direct to the firewirewall connector, then to a welded splice where it conencts with the other feeds. That's all sealed except on the inside of the bulkhead connector.