Some really good information about the Mule Team Knives can be found at the SpydieWiki, where they have a very informative article...
http://www.spydiewiki.com/index.php?title=MT_Mule_Team
MT01
Steel 52100
Release Date 01/11/2008
List price $39.95
Hardness 62 HRC. Independent reports of 63.
Link http://spyderco.com/catalog/details.php?product=283
Seconds Yes
MT02
Steel CPM M4
Release Date 10/22/2008
List price $69.95
Hardness 62 - 63 HRC. Independent reports of 62.5.
Link http://spyderco.com/catalog/details.php?product=364
Seconds Yes
MT03
Steel CPM S90V
Release Date 02/02/2009
List price $69.95
Hardness Independent reports of 59.
Link http://spyderco.com/catalog/details.php?product=384
Seconds Yes
MT04
Steel ZDP-189
Release Date 07/10/2009
List price $79.95
Hardness 65 - 66 HRC. Independent reports of 66.4.
Link Not available
Seconds No
MT05
Steel 9Cr18Mo
Release Date 10/14/2009
List price $20
Hardness 58 - 62 HRC
Link http://spyderco.com/catalog/details.php?product=426
If you can think of anything else that properly belongs on this table, please feel free to let me know.
Marion