http://www.mediafire.com/?76vkxkq7ksacf
That link will carry you (developers) to a page where you can download screamer 4x4, motor m4x and Insane offroad.
The Insane and Motor m4x are split up and must be joined by the software included in the folder.
To do this go download files including "Free-File-Splitter-v5.0.1189.exe".
Then put files together in same folder, open Free-File-Splitter-v5.0.1189.exe and go to merge, then chose a file and merge.
After they have merged you should the installation files.
For motor M4x, its a ISO and requires a image mounting software like power iso, which I use:
http://www.poweriso.com/download.htm