3/4 ton Rear Springs on a 1/2 ton

[68 Suburban]

I am going to be changing the rear springs in my burb. I want to get the firmer ride of the 3/4 springs. How much higher should I expect my burb to sit in the rear over the stock springs?

Also, if the truck will sit higher, do they make a dropped 3/4 ton rear spring.

Also, what is the proper procedure for replacing the rear springs. I am under th impression that the rear springs are not under compression like the front springs?

Thanks