5 or 6 leaf rear springs?

My 68 Barracuda had 6 leaf springs that had sacked out. I replaced them with Mancini XHD springs that have 5 leafs. The spring pack at the axle is thicker with the 5 leafs than with the 6 leaf springs I had and the 5 leafs are definately stiffer.

What I am getting to you need to be comparing spring rate and not the number of leaves. If you are using factory springs then you could compare 4, 5 and 6 leaf springs but aftermarket you can't.