I have talked with the tech's at the Support Center (800.232.3253 or 800.835.6100). They were able to tell me the actual part numbers for components for my Phaser 5550N (not supplies) that I needed to replace.
You might give them a try if you haven't already.
Thank you for the reply, unfortunately this particular setup requires a cable to connect the extra tray to the main printer unit. A picture of the cable can be seen in the documentation for the larger paper tray, but no part number is included.
Normally the machine and the optional tray must have connectors mounted on them, one male and one female that should connect when you put the machine over the tray 2. So you don't need another cable.
We have the WorkCentre 3345 and the Phaser 3330, WorkCentre 3335/3345 Paper Tray (520-Sheet) but we do not have the cable that connects the two units together. The paper tray will not work without the cable and I have been unable to find a part number or source for this cable.