Missing Disk Unit - Identifying

On the error screen saying the drive in ASP 1 Unit 2 it
says the Serial Number is 68-70B0E
This is the screen:
https://postimg.cc/FkGQ99nM

There are three hard drives in the system. I have marked
on each drive where they are installed:
Top
Middle
Bottom

Both the middle and the bottom drive have 70B0E on the
drive. I don't see the number 68 on either drive.

This is the middle drive:
https://postimg.cc/nMCc348W

This is the Bottom drive:
https://postimg.cc/2qVXsSzC

In the pictures I have marked the ID on each drive.
I'm guessing in DST there is a way to display ASP 1 Unit
2 and it's ID to determine exactly which drive it's having
a problem with.
I can hear all three drives spinning up.

Does anyone know how to identify which drive is unit 2?

Thanks,

Gary