This is my Thinkpad Dock I, paired with a restored IBM Thinkpad 760ED with a clean installation of Windows 98 SE.
I think internally people just called it an 'expansion unit', possibly because the original big fat Dock for the 700C was called an Expansion Unit.
My unit doesn't have it's own drive but from what I know there is SCSI and IDE internally for either type of drive, although to be noted it's only a half-height enclosure. I will look out for the CD-ROM adaptor kit.
The speakers are cool but not very loud - I expected them to be Powered but instead they're passive with no volume control of their own.
As you can see it has it's own lovely carry handle.
There was a special combination sold with this dock, offered in 1994 and branded as the Traveling Multimedia ThinkPad which came in two versions. The 755c with it's TFT came in at a premium at $9,175. The other was a 360CS version (with a DSTN screen) which would cost you a mere $5,699. I think DSTN wasn't the only variation but I'm not sure what the exact other differences were.
Supported ThinkPads
ThinkPad 360, 360C, 360CS, 360P, 360CE, 360CSE, 360PE
ThinkPad 370C
ThinkPad 750, 750C, 750CS, 750P
ThinkPad 755C, 755CS, 755CE, 755CSE, 755CD, 755CX, 755CV, 755CDV
ThinkPad 760C, 760CD, 760E, 760ED, 760EL, 760ELD, 760L, 760LD, 760XL, 760XD