looks like the 2.5 bay will accommodate this Dell caddy used in XPS 8940 and 6 other Dell models. YHNFX  Solved: XPS 8940, 2.5" SSD bracket? - Dell Community
This computer does not take an adapter of 2.5 to 3.5 inch. Please see the pictures of the width of the caddy bracket in the computer and the 2.5 to 3.5 adapter I bought. It will not fit. What 2.5 inch caddy can I use? [IMAGE][IMAGE]
Please help me find a caddy for Optiplex 7080MT XCTO