After 20Tkms of heavy use (hard acceleration, late braking with 400-500Kg on the bed) on the extended shackles my leaf springs have flattened out. Had the time to have the original shackles installed and this is what it looks like:
The upper 3 leaves are almost flat. Stubborn me, should've never loaded the rear too much with the extended shackles installed.
Let this be a lesson to people who want to lift your truck. It's ok to use taller shackles if you don't tow or load much in the tub. But if you do, AAL/custom leaf pack is a much better option in the long term. The stock springs don't have much arch in them brand new to begin with.