Was having a hard time finding anything that was specific to a single drive other than C:. I only needed a the total size of D: drives. I ended up using this:
(name of it & " - " & (total space of it / 1024 / 1024 / 1024) as string & " GB") of drives whose (type of it = "DRIVE_FIXED" and name of it as lowercase contains "d:" AND exists total space of it)
This seems to do the trick but always open for better ideas.
Thank you.