On eBay I cannot find a dual unit box, just big towers for 8 units.
In theory even boxes for tape-drivers (LTO, DLT) should be ok, in the practice: no, they are not, due to stupid design like custom metal stoppers which prevents me from installing a common SCSI unit like a DVDRAM.
One week ago a friend bought a DLT unit and it comes with a BOX that is physically made for a 2U SCSI 5.25" unit, but it has custom metal stoppers, and this is not good.
I am located in Europe, importing from the USA is very expensive. I'd prefer something within Europe.