Late-2015 27" iMac insides...

I'm working with a late-2015 27" iMac with a 4.0 processor and 16 G of RAM.

The user bought this machine with the 256 flash option. The only drive in this machine is the 256 G flash drive.

I know these machines are outfitted to also carry a platter drive, either on its own or as a "Fusion Drive".

I am supposing that this machine has a 256 flash drive down behind the logic board. That would mean the space where the hard drives goes is unoccupied. I am also aware that they don't have different logic boards for different configurations. That means the logic board in this machine is ready to receive a second drive. So, here is my question:

Is everything else there for me to put a drive in place? What I'm really asking is: is the connector cable there? I'm assuming I can buy the rubber housing and bands online. But, that connector cable, is it there? Or do I need to order that as well? Can I?

Any insights, especially from folks who have done this before, are welcome.

Thanks!

Follow these instructions to take the iMac apart and see what it looks like inside and decide how you should proceed.

Yeah. I was looking at that last night. Those take-apart and replacement guides are quite good.

I was hoping somebody here has specific knowledge about the parts available inside this machine with this configuration. Then I can know what to buy ahead of time, if anything.

I suspect this will help: http://www.ifixmaccomputers.com/923...Kz8I8BZsO6HPget2WZJTe8SkluYb4m1BoCoYQQAvD_BwE

I know I'll need this for sure with a third-party drive: https://eshop.macsales.com/item/OWC/DIDIMACHDD12/

I just want to find out about that first piece. Moreover, on the very slim chance if is a different logic board that does NOT have that second drive hook-up, I wanna know now.

Basically, I want to know everything I can before I peal that darn screen off.

Give OWC (Mac Sales) support a call and ask their tech support about their mounting kit. They have a toll free number and their support staff is top notch. I believe you will need the mounting kit but am not 100% sure that the mounting bracket is there or not. Anyway, OWC support will be able to tell you one way or the other.

For comparison, check DVwarehouse:
https://www.dvwarehouse.com/