the five leaf are a more universal spring for people who just want new springs, so there are stockpiles of them, and they're cheap. the only people who want the four leaf are people who might notice that their car came with it, and want it to stay original. the 5 leafs fit all F bodies and X bodies of that era. the 4 leafs were more specific.

the five leaf will put you above stock height. yes the rear was a little lower from the factory. i dont know if the 4 leaf sits right or not. if they are not rusty you can get them rearched.

check all your bushings too. subframe and all. they can make it sit crooked too. mine sits low on the right rear too. i used to think it was from body twist from hard acceleration, but i'm leaning towards blaming that yellow LF fender that was on my green car when i bought it. it used to lean real bad before i did springs and bushings. now it is barely noticeable.