I've heard (and seen) that sometimes when you uninstall an older version of Sonar that plug-ins get removed that are common to both versions.
V-Vocal & R-MIX** that come with X1 are not part of X3.
You might be able to install R-Mix by itself, but don't think so with V-Vocal.
Run the X1 installer and see if they are listed as part of the plug-ins.
If so you, uninstall X1, install X3 then install X1 plug-ins.
Personally I rarely uninstall the older versions.
They still work & I don't think they take up that much disk space.
**correction - it was pointed out in one of the following posts that R-Mix actually came with X2.