I just did a shock/spring job myself. Every time I slowly rolled out of my drive way-my machine sounded like it was treading mud, "sloshy" sound. I would change them both at the first indication to take the pressure off the shock mounts on the frame. It is much easier to change a shock than to fabricate a shock mount.
Acquire enough Jacks to safely support the entire weight of the machine and start replacing-it's easy.