Which 4 inch lift?

[Mr-Jack]

centered referring to the spring...meaning the center pin that holds the leaves together. is it equal-distant to each bolt hole. Length is measured along the top surface of the spring.

originally...meaning the stock springs...and were they centered?

i'm thinking about using this for my 67. just trying to get some information from people. There's a member here that used the flip and it moved his axle forward about an inch and a half.

and the overall lift differance between a 4.5" and 6" shackle flip is only 3/4" overall. not really that noticeable. I plan on welding new perches in and getting a nice set of driveshafts anyhow.

like i said the expense isn't the problem, but the right parts and information prior to starting the job for me is. This isn't my first rodeo, just trying to figure out these symetrics of the 67' rear springs cause the 67 & 68 rear springs are unique. Plus since i'm halfway around the world right now, i can't just run out and measure for myself so that's why i'm asking on the forums. I purchased the truck and had it delivered to my house and want parts sitting in my shop waiting on me when i get home so i can start.