7090SFF odd has 3 components: bezel, latch, bare dvd. you may be able to order the latch (LTCH) directly from Dell via online agent chat, I think. or you can buy the bezel and latch on eBay.  ask seller to verify p/n. [IMAGE] [IMAGE]       [IMAGE]    
Why does Dell make it   near impossible to add things after purchase!?  I have a 5090 SFF that I would like to add a DVD drive to.  Besides the confusion of the drive itself vs the bezel you also have to consider the retainer.  Seems the X090 series doesn't use the blue plastic piece but a metal one. Can someone who has a DVD already post pics and part number please? 
3090/5090/7090 SFF optical drive