If you can, get a 1965 Bulkhead connector. I put one in my 1964 Valiant. The reason is that it has 2 large buss-bar feed-thrus for the thick ALT and BAT wires, which avoids the common "melted bulkhead" problem. It is ~1/8" taller so had to slightly trim the firewall hole, but you might be doing that anyway coming from a 1963. BTW, 1963 also had the buss-bars. My guess is they noticed a problem w/ melted terminals in 1964's so brought it back in 1965 (albeit with 2 larger connectors). Perhaps a bean-counter nix'ed that so they went back to running thru Packard terminals, which caused endless problems. Re the wiring, the 1965 FSM shows that (search). In 1966, they moved the wiper motor into the engine bay, which required a 3rd connector on the bulkhead.