StrawberryPie,  Unfortunately we don't have an upgrade kit for the R730XD . Due to differences between the multiple chassis models offered with the R720XD, the chassis option must be selected at the point of purchase and cannot be changed or upgraded at a later time. Sorry I know this isn't the answer you were hoping for.  Let me know if this helps.
Hello, I bought a refurbished R730xd without the rear 2.5" drives, and am now investigating how to add them. The system does not appear to have come with the necessary mounting hardware to actually put drives in the two rear mounting locations, so it appears I have to find mounting brackets and any associated cabling that may be necessary. Googling around, I have not yet been able to identify what the part numbers might be. Can anyone point me in the right direction? What are the necessary parts to make the rear drives work? And also, where do they connect or plug into? Thanks in advance for any help
Part numbers for rear drive mounts for R730xd?