Heater instrument panel differences for 67?

Probably a bit late reply but yes...kinda...I have a LATE production 67 cuda and the only spring was on the right hand side hinge. the other hinge did not have one. My 67 Dart GT was made on Dec 5th of 66 and it has a spring on the left and right hinge. The left one wore unevenly and basically oversized the rotating pin and it closed cockeyed. I have a suspicion thats why they went to one spring and then got rid of the 2 hinges altogether in 68+

I think what I found most interesting was that the hinge definitely appeared to have a spot to put a spring at least. That being said, I'm having enough trouble getting it to not hit the A/C ducting behind the dash at all. I think I finally got it, but it's wrangled in there pretty good. If I remember correctly, I had to go up and over the top of the glovebox to get the ducting out of the way. If I tried to route it the more direct path of going under the glovebox, the hinge would hit on it either open or closed. Also, for whatever reason it seems to be staying shut better now than it did before, so the need for the extra spring has lessened.