When i was finding ISOs of super-rare Windows Vista betas. I founded this very weird file on a long forgotten forum. It has isos of OSDKS that were made to create new builds.
I even founded a OSDK Windows .NET Server 2003 Release Candidate which was used for very early pre-reset Longhorn builds) and a OSDK of a Windows Server 2003 Service Pack 1 beta which was used for builds like 5000)
They function somewhat differently than the built versions.
Heres a list of some of them.
Milestone3OSDK-Kit: Has a gadget maker tool
MS4OSDK: Updated gadget maker tool
MS4OSDK-Revision-1: Updated gadget maker tool. Has ability to toogle gadgets on and off.
MS4OSDK-Revision-2: Failed revision, Somewhat broken.
MS5OSDK: Only used for 4029.main.030619-0000. so the other Milestone 5 builds are built with an unknown version named MS4OSDK-Revision-3BETA
MS6OSDK-BETA: Beta version. only used in a unknown build after 4030.
Milestone6DevOS: Includes new DWM editor feature with a unfinished WinFS editor codenamed EditFS
Milestone6DevOS-Rev1: WinFS editor complety finished.
Milestone6DevOS-Rev2: Fixed a unknown glitch
Milestone7DevOS: Edited version of Milestone6DevOS-Rev3Beta
4074DEVOS (Codename Milestone7DevOS-Revision1): Unknown but seems to have more features related to Aero included.
Milestone8DEVOS: Somewhat broken.
DEV13TEST1: Seems to be based of Milestone8DEVOS. However doesnt work as it is missing a dll
Omega13DEV: Restarted OSDK. Has a Game Creator with a Aero editor.
Beta1Kit: Used for most late-Beta1 builds and Pre-Beta 2 Fork builds
Beta2Kit: For some bizzare reasons it seems that all Beta 2 builds were created in this kit. Also early Pre-RC1 builds are created in this kit.
PreRCkit: A upgraded version of Beta2Kit.
RC1kit: Removed useless functions
RC2kit: Rebranded RC1kit but with somewhat a new feature.
EscrowKIT: Used for RTM Escrow builds.
ReleaseKIT: Possibly used for finallising build 6000.
ServicePackKIT: used for SP1 and SP2 of Windows Vista
These run differently from the real builds of vista however i founded this very rare screenshot
This screenshot shows Beta2Kit patched to run Windows Vista Beta 2 Build 5308. however explorer doesnt work and help software doesnt work.
Of course since Build 5308 and Beta2Kit are all different Operating Systems, Beta2Kit software doesnt work with 5308.