what lowering springs are you using on your 67 Skylark? i see they list the same springs for 64-67 but doesn't the 67 use a different rear spring since the perches are different on the 67 axle vs the 64-66?
Check the Hotchkis web site, I have a 65 GS and used thier springs. Lowered the car 1 inch all the around, still good quality ride.
I'm also using Hotchkis 1" drop springs. In my case the original springs were worn out and the car handled sloppy but I liked the stance and didn't want to change it, especially by going with stock replacements because it has been my experience that they make the car sit higher. The Hotchkis springs landed the height almost exactly where it was with the stock springs and it made a huge difference in handling. The ride is firmer but I was surprised at how nice it still is. After adding 1 5/16" front sway bar, 1 3/8" rear bar and a set of KYB Gas-A-Just shocks, the car handles like it's on rails.
I used Eibach springs and I have 17 inch wheels. I think the 67 mounts are different as they dont bolt on and just have the raised round locator on housing instead of the flat perch with a hold down disc and bolt. I think they sit maybe a 1/4 to 1/2 inch to low in the rear.
See the attached pic. The one on the right is '64-'66. The one on the left is '67-'72. It's the top that changed.
