Read this;
3rd Gen 4Runner Lift Information and FAQ's
There are no rear springs between those. You could put 906s on and put a small spacer in there. I have 890s I like the little bit of rake and the spring rate is less than the 906s so they're a little softer and when there's weight in the back it stays level. You may want to consider saying closer to 2" of lift because as you approach 3" you start needing to level your panhard bar, and will need extended bumpstops and extended swaybar links. I thought when I did my lift I wouldn't need those but for me, I wanted a better ride and all these things really helped.
Threaded Mode
