67 vs 69 dart wiring harnesses

Not exactly. When they added signal lamps on hood or fenders they moved some wire to different ports in the bulkhead connectors. One could match a 68,9 harness to a 67 harness with both wiring diagrams. Well except for some wire colors, like the wires going to headlights. Those changed too.
Also for the automatic trans builds, the reverse lamp switch and wiring moved from inside the cabin to outside ( from shifter to trans ). Those just the first differences that come to mind and all lighting related. Fewer difference are found in engine harness. Under dash harness varies mostly at wipers.
So yeah it can work but not a direct swap.