Very different connections at the bulkhead. Also '65 introduced the fusible link IIRC.
Then there's the mystery of the Canadian variations which did some things differently, like that starter. That uses a remote solenoid IIRC
Yeah there's been so much add/subtract splice solder under there it's anybody guess. I'm going to chase it all down and run continuity checks between the under dash and engine bulkhead connectors to validate. The ones I have messed with are consistent with the 64 diagram. It's been converted to electronic ignition already with the /6