I want an Apple Certified large capacity drive for 2008 Mac Pro

Question

I have a Mac Pro (early 2008) filled with all Apple Certified hard drives in it.
I want to put the largest available Apple Certified hard disk drive into one of the bays.
Apple won't sell me a drive. They say I have to bring in the computer and have their service people insert a new drive.
So... They have the drives. They just insist that they... not I... do the replacement and charge me for the drive and installation.
Three of the drives were replaced BY ME at various times since I bought the computer in 2008. They sold me those drives over the counter in my local Apple Store a few miles from my house.
How can I duplicate that without losing custody of my computer for days while they put in the new drive?
Suggestions:
Can I take out ALL the drives, leave them home, and bring in the empty chassis to let them put the new drive?
Can I take out one of the "shells" that hold drives, empty it of its current drive, then take them that shell and have them populate it?
What are my options?

Answer 1

Memory lane.... ? "Once upon a time, far and long ago... disk drives and controllers had to be closely mated and sourced..."
SCSI drives and controllers, and later SAS, you could make an argument - maybe - and buying a set of drives, with extra spares for later when one of them failed.
Enter stage right: DIY and CIP
SATA drives are off the shelf. OEM does not matter in a system that does not use specialized hardware RAID
SSD drives can require firmware for compatibility so I could make an argument for an Apple SSD which were offered as BTO and because TRIM on 3rd party devices - because OS X looks for an ID in the product string to say "I am an Apple SKU" or not, and that is the beginning and end of that, and only matters with Yosemite for all intents and purposes.
So then you can read up on StorageReview.com and others and see what the Leaderboard has to say as well as elsewhere as far as what storage devices.
But no matter what, the same age old wisdom of having system  drive, data, scratch (for those large database sorts and such or editing in graphics and video), backup (so it is online). System = small and fast, 15K SCSI no longer being king, it is now PCIe-SSDs that offer 10x or more faster, and 0.01 nanoseconds delay in seeks and latency with large queue depth for multiple IO's. The ability to load and read lots of files at 1000MB/sec or faster is perfect for system, and writes of 900MB/sec and above don't hurt.
Then use 4TB drives for data, cheap large and still fast and outstanding.
APPLE HAS NEVER UPDATED THE DRIVE COMPATIBILITY SPECS when new drives become available, leading people to mistakenly think or ask and wonder "can my Mac use drives larger than ______ (where 750GB was the largest capacity and was for some odd reason listed as such) instead of something like "SATA II and higher" Where SATA 3.1 (?) is the current version and is backward compatible.
PCIe devices are often listed as "PCIe 2.x" or 3.0 and my Samsung XP941 with Lycom adapter is nice enough to list and state that while it is PCIe 3.0 compliant it also supports and backward compatible with PCIe 1.0 and above. It won't get the same bandwith/performance in PCIe 1.0 - 2.0 but it works perfectly.
The firmware of controllers determine support, and sometimes though less and almost unheard of with standard "rotating spindle" disk drives (NAS and hardware RAID being the exception that makes the rule).
SSD has changed and evolved faster than anything I have ever seen in computer technology and storage specifically. A year seems like a lifetime in evolution. And yet... my old 2006 (turns 9 in August) was discovered to fully support PCIe-SSD like the latest device in the nMP and the XP941. Amazing but I guess Intel knew something when it designed the SkullTrail systems and EFI 1.0 back in 2005. So the latest SSD tech is supported in a 1,1 (thru 5,1) running Leo or higher.
There have been issues with the size and screw holes of 4-8TB drives (and yes you can use those too). And when Apple created Fusion drives for the iMac and had trouble with Windows Boot Camp the changes in formatting using Disk Utility turned into a Windows XP 32-bit problem formatting drives larger than 2.2TB in Mountain Lion 10.8.4 and above. I am still scratching my head over that one. Even as it was documented and confirmed. (And no it does not reflect on 3rd party or only with drives that are not labelled Apple OEM
Others can probably make a shorter more succinct case without the long history and rambling my prose is given to as I wonder around in the cobwebs