Fj80 coils on the rear
 

I have looked at so many threads and builds, all I'm looking at is to put fj80 coils in the rear of my 91 runner. I already have the 4" 4link with 2" pucks from pro comp. The right side coil is already sagging, haven't had the lift for 5 month's. I just want 6" and I want to know what spring I need from the fj to accomplish that. Thanks