So happy with X3 that I deleted X2 to get more room on my SSD. When I launched X3, the plug counter reports 30 plug ins less, from about 180 to about 150. I can't figure what I lost other than V-Vocal and R-Mix. Those I expected to lose but no idea why the rest vanished, or exactly what they were. I'll likely find out given enough time, but I didn't realize there were that many X2 dependent plugs.

They do not depend on X2. Most likely you set folder pathways in the Plugin's manager. Go in and check if you have all folders with Plugins listed for scan.

I can tell you analyst , tape emulator and amp sim are among them.  Probably a couple of other cakewalk plugins too

I guess a question would be: Which CW plugins do you still see?
 

I'll likely find out given enough time, but I didn't realize there were that many X2 dependent plugs.

There are not 30 dependent X2 plugins. Maybe 3 or 4 plugin, if that. 
 
So, I really do not think you lost 30 plugins deleting X2 after the X3 installation. You probably just need to set your VST scanner to scan the correct pathways to where you have your plugins installed. This is something you'll need to figure out as they can be installed anywhere on your PC.
 
CJ
 

I agree.  i doubt there were 30.  I think one of the cakewalk delays is missing too

One thing that may be happening could have to do duplicate plug-ins being removed. Check your Program Files (x86)/Cakewalk/Vstplugings folder. If there are any duplicate plug-ins between this folder and the 64bit folder the scanner will scan them and then remove them. The app is designed to use the native binary if possible. 

Thanks for the comments. It looks like Lance nailed it. I did a search for duplicate files and found hundreds. Between Sonar and 3rd party stuff I've got duplicates of just about every sample file and all the install files. I guess mega hard drives have made me lazy with the housekeeping. I just can't bring myself to attempt a purge but I really should.