Chassis Guy/gals that understand SS Spring....Help!

I have read this all many time before........but this time i got a few more things out of it.
I purchased the 3600 pound E body springs before and this time around a when with the 3800 pound spring.
I also when out and measured the back half of my leaf spring.
I never measured the original SS Spring, but i had to remove the rear valance so spring/shackle would clear or could be installed.
I know that these new SS Springs i still could not install my rear valance without some surgery to it to clear the shackles.
So it's not like they screwed up the spring rear segment.......or they did! 20+years ago, and still havent fix it! Either way i will just deal with it.
Interesting just the same.

My SS Springs.PNG

@famous bob I can see why it work well even in a heavy car like yours (02-03 springs) look at the lb/in rate.
Everybody love the 02-03 on there A Body........but there intended for a stick only.

Says shackles should be no longer then 8-1/2" long for handling reason.......Mine are 3-1/2" long