Hitachi Travelstar Drive discrepancy

I've got a few Travelstar drives from IBM T22 laptops. The laptops used to
be in a fleet of thousands. The drives are supposed to be 40 GB, per the
drive label and the spec sheet I dug up from hgst.com

However, all I can get out of these, on the T-22s, is 30 GB. None of the
partition tools I've used...PartMagic, DriveImage, BooiItNG...show more than
30 GB on the drive. Just tried the drive in a desktop to eliminate any
potential BIOS limits, and still 30 GB.
Odd. Any ideas?

Travelstar 80GN, model IC25N040ATMR04. I guessed a mislabeled drive, but the
BIOS shows the same model#.

-John O