Chris is correct in that the inserts are genuine originals. After studying this a bit more, this looks to be a '66, not a '67. The dash and taillights give it away. Of course someone could have changed both but I doubt the dash would have been. I have seen on a quite a few '67 dashes one '66 knob in the middle. Can't remember the function for that knob but really odd seeing this. Will look for pictures and possibly post if I get time.
The tailgate has been replaced too - no yellow paint underneath the sprayed over blue. Of course the grill has been replaced with a later one. As for the 289 motor, March 1966 was the first month/introduction for the V8. I have one btw!
The seller thinks it's a '67 but I'm sure it's a '66 if someone can get the vin. And Bobby is right, open that hood will tell a lot as well.
On the tailgates, early '67s had the '66 gates, several months later the '67s wore the newer gate. Again, I have seen this many times.
Just thought I would add my two cents worth. Vin yields the ultimate truth!