Ey up battlearrow, you must remember that nearly all the built-in assets were purposely made for TC3 and therefore probably won't work in another earlier version. Why don't you purchase TC3 directly, you can have it installed on your PC as well as any other Trainz version, TRS2004, 06, etc.
You can of course, move your TRS2006 content INTO TC3 with a bit of fiddling and faffing about, after you've installed it, but the choice is yours......
Cheerz. ex-railwayman.