@ajcooke01 Well there is a blade and it is already taken by the SSD part of the Fusion Drive.
Jorge can of course upgrade just that blade BUT:
- He will have to pull the board out of the housing, which is always a bit risky;
- The blade costs a lot as they are Apple proprietary.
On the other hand, SATA SSDs are not that expensive and easier to reach within that iMac.
Jorge can instead replace the HDD with a 960GB SSD and "re-build" the Fusion Drive and in my opinion it is always worth it for most applications. And possibly purchase an enclosure and use the 1TB that he would have pulled from the iMac as an external Time Machine back-up drive or for additional storage space.