where can i download TestStuff??

You don't download it. It's a mode that can be enabled in the beta updates, and when enabled (as I have heard) weird stuff happens.

If you have the 3.6.28.0 beta installed, read its readme file for more info.

but that only enables A particular version of Test Stuff and doesnt allow access to the others.

if your into memory hacking then this is a simple way to enable the other versions of it. http://forum.team17.co.uk/showthread.php?t=34025

I'm not exactly certain where in his post he asked for a particular TS version, but then again, I've started to believe a long time ago that you see things others don't.