I'm still looking for detailed photos of the progressive linkage. I found these by going through old ebay auctions. This linkage is very different than the linkage I have on my non-prograssive intake, but very similar to the linkage on the buick intake that was posted.
On this picture it looks as there are adjustment screws of some sort.
Here you can see that the progressive set up uses both holes cast into the center runner to hold pivots and linkage. On the non-progressive setup the inside hole just has a plug filling the hole.
Any and all pictures or detail are welcome.
Thanks,
