In case you were wondering "Where can I get more content for my Plant 3D software?" I have some news for you: the Autodesk Exchange Apps store has many free and inexpensive catalogs and specs available for you to download.
Go here: http://autode.sk/1W4cCFG
Or just go to https://apps.autodesk.com and select the "Catalogs & Specs" category under the "AutoCAD Plant 3D" product store.
Some of the content available as of today in the Autodesk Exchange Apps store are:
Below are the catalogs and specs currently shipping with the product:
And then there are catalogs under consideration (see table below). If you want to submit a request for new catalogs, send an email to email@example.com and they will add it to the list:
Be sure to download the version that is compatible with your version of Plant 3D.