The wire colors and connections on the bulkhead are the same. You will likely need to change the park/signal light connectors I think they are different. You may also find that not all component locations are the same 66 to 67. I’ve never owned a 66 and haven’t spent much time under the hood of one. If buying a new 66 harness is out then adapt the 67.
Elree's right as usual. I sort of cheated to do a search. Went to M & H's site and looked up the part numbers for both years. They are different for both the gage and idiot light forward harnesses. http://www.wiringharness.com/
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