Yeah which is absolutely bizarre because they aren't stock. I've never heard of a replacement stock spring narrower than normal. And I'm pretty sure even 2-2.5" lift springs don't get arch either.
3" from floor to bottom of spring.
Those springs are exactly the same height as a 1/2 ton stock spring.
That's not how you measure a lifted spring. You cant go off of that. You have to measure how much the truck is lifted once all the weight of your vehicle is sitting on them.
I have 2 brand new 4" springs sitting on my shop floor and I just measured from the floor to the spring and they measure 6 1/2", but when the trucks weight is on them they will lift the truck 4" from stock ride height.
I would take them back and get your money back cause that isn't right! No way in hell that they didn't know that they sag like a stock spring! I wouldn't put up with that ******** if I were you!
The stock springs are narrower at the U bolt then at the spring hanger. The after market springs are just the same width from end to end. A stock front spring has 3 leafs where as an after market spring has 5 or 6 leafs, that's where the after market spring gets the extra strength from.