I replaced my rear control arms last weekend.
From memory, this is how I did the lowers:
* Note that many of these bolts will be corroded and a nightmare to remove. I got lucky and didn't have to cut any out. Coat the bolts liberally with grease when reinstalling to keep them from seizing in the future.
* Raise car, support with jack stand, remove wheel.
* Support the spring arm at the spindle with your jack and remove the bolt.
* Lower the jack to separate the spring arm from the spindle - removing the spring tension will make it easier to maneuver the spindle. No need to loosen or unbolt the toe adjusting end.
* Unbolt sway bar link from LCA.
* Unbolt shock absorber from LCA.
* Remove ball joint bolt from spindle - after the nut is off, you will probably have to drift it out.
* Use a ball joint puller (like this:
https://www.bavauto.com/bmw-puller-b880 ... MEQAvD_BwE )to press the ball joint stud up from the bottom out of the spindle.
* Take a picture of the camber bolt position.
* Remove the LCA mounting bolts.
* Clean and grease the spindle stud hole to make it easier to get the new one in.
* Drive a cold chisel or big screwdriver into the spindle clamp slot to spread the stud hole slightly.
* Put the new LCA in place and drop the stud until it is fully seated - much wiggling required and I had to smack the chisel in pretty good to get the stud to go in freely, but I left no marks or gouges on the spindle so it's not too aggressive.
* Look through the ball joint bolt hole to make sure the stud groove is aligned with the hole - if it's too shallow or too deep the bolt won't go through
* Pull the chisel out - wiggle it up and down and it will squeeze itself out
* Install the new ball joint bolt - the Meco LCA come with a new bolt and nut, note that the stick bolt has a 17mm head but Meco bolt has an 18mm head. Don't force it! The bolt will lose the fight against the hardened stud if the stud groove is not aligned.
* Reinstall the LCA mounting bolts, ballpark the camber setting from your picture.
* Reinstall Sway bar link and shock bolt.
* Jack up the spring arm to the spindle to align the bolt holes to get the bolt started - it won't go all the way through.
* Jack up the spring arm higher and higher until the other holes align up and you can push the bolt the rest of the way through.
* Reinstall the spring arm nut.
* Put wheel on etc.
* Get a 4 wheel alignment. Make sure they adjust the rear to "nominal" not just "in spec". Pathfinders are very twitchy.