8\" springs in rear... or add-a-leaf on 6\" springs? as soon as the bank account grows, the '81 is gettin 6" springs in front. i know the fiberglass top makes the rear sag a bit. should i just go for the all 6" spring lift and install an add-a-leaf? or should i just go with a pair of 8"springs in the rear? if add-a-leaf is the way to go, do you install the leaf while the spring is on the vehicle? or just out of hte box? i'm a "suspension greenhorn", so please bare with me.any help is appreciated.