[UPDATED]FOLLOW-UP
Finally had time today to start the install on these. They have MAJOR interference on the motor mount on the passenger side. I wouldn't mind clearancing a bit...but it would have to be maybe 1/4" and I'm not doing that. Moving to some Hookers, which is what I should have bought in the first place.
You can see from the pictures I posted in the thread below the difference between the two headers. I guess the determining factor is how far forward your mounts are.
http://67-72chevytrucks.com/vboard/s...13#post2017213