I am writing to report a success, not to provide step-by-step instructions, in fitting a second generation simultaneous dual-band MB998LL/A Model No. A1302 firmware 7.6.4 (originally contained the Apple-branded variant of the 2TB capacity Western Digital WD20EADS 2TB 7200 RPM 32 MB Cache SATA 1 1.5 Gb/s Caviar Green made 28 Jul 2009) with a Hitachi HGST (now WD) SKU# 0S03355 Deskstar 4TB 7200 RPM 64MB Cache SATA 3 6Gb/s drive. I am certain I am not getting 6Gb/s out of the drive in the TC, however, all of my machines were able to access their sparceimages on the upgraded TC. Some details: The choice was between a new 802.11ac 3GB TimeCapsule at $399 and purchasing a Hitachi Travelstar 4TB drive for $220. If there was a 4GB option for the TC, I would have taken that, but there was not. Adding 1TB and the same hassle of somehow getting the old sparceimages into the new TC had me keep the old TC. Basically this offered the most time between repeating this hassle again. Instructions for opening a TC (requires a heat gun or other heat source) and for cloning drives will be found elsewhere. I did these from memory, so, I do not have these sources at my fingertips. Please find them yourself if you need them. I inserted the new unformatted 4TB drive into the old TC. Using the Apple AirPort Utility 6.3.1 I formatted the drive. I removed the drive and placed it and the original drive in a MacPro 1,1 running Lion OSX 10.7.5 (11G63). The old 2TB WG drive had three partitions, APconfig, APswap and Data. The new 4TB HGST drive had three partitions APconfig, APswap and Air Port. I used Carbon Copy Cloner 3.5.3 (http://www.bombich.com/) to clone each of the old partitions to the corresponding new partitions. The old WD 2TB drive ran at 1.5 Gb/s in the MacPro's bus according to Apple's system information application. The new HGST 4TB drive ran at 3Gb/s, which meant, unfortunately, that the transfer would occur at 1.5 Gb/s. It took 12 hours and 15 minutes to transfer 1.99 TB of data at 1.5 Gb/s. Let's check the math. (1.99TB * 1024 GB/TB * 8b/B)/(12.25 hr * 3600 s/hr) = 0.37 Gb/s. So, I got less than a third of what was advertised. I did not investigate this. Once the transfer was complete I renamed the "Air Port" partition to "Data", as on the original TC. Now the pathnames from my Macs to their sparceimages would be the same as before. Otherwise, you may need to "inherit" an old backup http://pondini.org/TM/B6.html. I replaced the new HGST 4TB drive in the TC and restarted it. I commenced backups from all of my Macs successfully (Lion, Mountain Lion, Mavericks and Mavericks Server). I have not tried to do a restore yet. If I have any problems I will report them here.