Optiplex 790 SFF drive caddy

The official way to do it in most dells is to get the 2.5 to 3.5 blue plastic stacked 2.5 inch drive adapter R494D that snaps into the 3.5 inch drive holder. You can also use the Silverstone adapter has all the mount points of a standard 3.5" hard drive, and it's $12. It holds two 2.5" devices stacked just like the R494D does. Power and Sata port will have to be stolen from the optical drive or Y splitter used for power.  The R494D snaps into the 3.5 inch caddy like a matruska doll.

At this point, I'm looking to fit a 3.5" drive only, so no need for R494D. I believe the P/N DN8MY is correct for the Optiplex 790 SFF, but I know from first hand experience that P/N YJ221 is not, which is what I think is shown in your picture and whilst OK for desktop/MT, it's not SFF . I suspect there are other P/Ns that match the DN8MY, but have not managed to pin down exactly which ones.

dn8my is the inside  r494d fits inside the 3.5 caddy

http://www.amazon.com/gp/product/B00MNMOBSA/ref=pd_lpo_sbs_dp_ss_2/181-0030922-5581416

Yes. I have the metal cage, I even have the DVD caddy, so just need to source part that holds the 3.5" drive. It looks are though P/N DN8MY, 1B31D2600 and I think C-3598 are valid, so the question is... are there any other parts numbers that are equivalents? Quite a few re-sellers are not clear on the exact part they ship and confuse similar items for non SFF machines.

To conclude, I have discovered  P/N DN8MY is reliably the correct part number, followed by 1B31D2600 and C-3598. However, some sellers (and not just ebay) can advertise incorrectly so check the details carefully before purchase.

I used the Silverstone adapter to mount an SSD and spindle drive in over-and-under configuration.