Hello,
I just did mine.
This is not an easy job!
There is a procedure on this website on how to replace the guide rods. Its confusing though, they seem to miss out a piece.
Before you remove anything count the number of threads on each side.
For extra measure I painted my thread with white paint, so I new how far to screw on the new ones.
The easiest method is to remove the springs.
However, I did it without, not easy though. I removed the bolts for supporting the suspension and the springs and lowered as far as it would go. Be very careful the spring doesn't pop out. On one side I did, it flew across the gararge, very dangerous!
The problem with doing it without removing the springs is the rod does not unscrew sufficiently to remove the unit. It gets caught up with the body.
If you could remove the rod at the suspension end, it would be Ok. However its near impossible to get to it because the spring covers the bolt.
Sooooooooooo, best method remove the springs.
Good luck
Brian