My 2004 V6 4x2 4Runner suspension seemed shot after 100k miles. A few weeks ago I purchased a set of coilovers and shocks off of an 2011 Fj from The Parts Whore. After some research we determined that they "should" be an exact crossover fit however I was not able to find a definite answer anywhere. This write up is for anyone looking to do this switch in the future.
Yesterday I spent roughly 4 hours installing the new set up on the 4Runner and only had two minor hiccups. The first issue was getting the front coils into the bracket on the lower control arm. The width of the receiving cylinder on lower mount of the shock was about 1/8" wider than the receiving flange on the LCA. I took a grinder to it and eventually it fit. The second issue was getting the old rear shocks off as I did not have a lift. I chose to use a sawzall to cut the shock out. The Fj shocks were an exact fit. Outside of that all the bolt patterns and sizes lined up perfectly.
In summary: The coilovers are 1/2" taller and quite a bit beefier from stock. The rear shocks are about 1-1/2 times bigger than stock. The larger set up provided a 1/2" of lift and eliminated the rub of the BFG 265/70/17's. Although the lift wasn't intentional I will take it : ) After test driving the rig I was able to tell that the ride was somewhat stiffer but an excellent improvement overall. Due to the height difference I will be getting a front end alignment immediately.