Dash lights will not turn off!! 72 dart

Wiring diagrams are in the service manual(s). '72 may have a Body Manual with additional electrical diagrams. Earlier years everything is in the chassis diagram. www.mymopar.com --> service manuals
The diagrams will show which wires connect to which position in a connector. They are generally accurate although occassional mistakes will be found, and sometimes the exact routing was probably changed when the harness went into production. For example a junction will be mae at a terminal rather than welding a splice.

Alternator output wire.
Some of us have run a second parallel wire to the ammeter. This provides a shorter path for battery charging while keeping the original path to the main splice. A similar arrangement using a wires through a grommet was implemented on cars with rear defrost grids, and another variation on this idea was provided as a 'fleet' option with higher output alternators (and larger batteries too).
Search for those terms and you should turn up at least a few posts showing each of these wiring arrangements.

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diagram of what I changed on my '67
https://www.forabodiesonly.com/mopa...2-21-for-fabo-and-fbbo.489486/post-1973473507and a photo Factory ammeter