Rear window louver question

[Ghoste]

I have asked this question on a few other Mopar forums and no one could answer it so maybe someone can here.
When it comes to the rear 1/4 windows on F-body Road Runners, why do some of the louvers have horizontal fins and others have vertical ones? I have not been able to discern that it was a model year thing only that some go one way and some the other.

[76beeper]

Ghoste - the 76 & 77 models have the vertical louvers and the 78 to 80 models have the horizontal ones.
The vertical louvers are held on with double sided thick tape & the horizontal ones have clips to hold them on.

[droptop]

Sept 16, 2009 5:58:52 GMT -5 76beeper said:

Ghoste - the 76 & 77 models have the vertical louvers and the 78 to 80 models have the horizontal ones.
The vertical louvers are held on with double sided thick tape & the horizontal ones have clips to hold them on.

I agree with 76 beeper. The vert. ones are taped right over the chrome window trim.