It was my understanding the 67-69 grills and taillights were insterchangable. Which would make sense as the 1/4's are the same as are the fenders. (with exception to the marker lights which don't matter in this case)
it would make sense except they are not... 67's have about a dozen things that are different from a 68, and from 68 to 69 there is about a half dozen.
I promise you the tail lights from a 68 will not fit a 67 without some work. its not a big deal but it just takes time. The sheetmetal could not be more different in the bucket.
as i stated earlier in 69 they moved the head light around to prepare for the 70 model year, its something like 1.5" to one side and either sticking out more or shallower (< think its this one).
as i recall ive done one 67 to 68 conversions and cant remember which one it is lol