-67 snd 68-72 differences?

I'm looking for SS exhaust kits for my '67 Belvedere and it seems like everyone makes a kit for 68 and up cars but noone touches 67 and earlier. Is there that big a difference from 67 to 68?

Its not just exhaust parts, suspension and brakes are the same too.

It's the tail pipes that are the big difference. On a 67 (say a GTX) they turn out near the corners of the car rather than just follow the rails straight back. I don't know if it would be possible to get a 68 up set then have a muffler shop fit the tail pipes to the car.

Also, if you're using manifolds (correct 67's) I think the flange on the driver's side is "clocked" differently than on a 68-70

I'm using headers. My exhaust follows the rails straight out the back. Maybe its just where the hangars are located...

how about RT