Optiplex 5055 SFF 3.5in HDD caddy

I'm trying to find a part number for the 5055 SFF 3.5in hdd caddy. The system came with a metal cage and plastic caddy for two 2.5in drives but I need a single 3.5in drive. I have seen photos online for other optiplex models but its hard to tell if they would fit in my system. I called dell technical support, they didn't know so they transferred me to sales who also didn't know. I was given the email address of a solutions specialist but he has not replied back.