Drivetrains beyond the KOP

[twolf]

Obviously when you attend a regional you see the teams that have been at this for a long time that have very non traditional drivetrains that might be skid steer, tank tracks or whatever else. We are wanting to acquire some of these components to test them for next year so we can move beyond the casters and pneumatic tires. Is there a good site to buy this stuff? I have checked out AndyMark and we used their Omni wheels this year.

Also, do you have to use the kit transmissions? Are the AndyMark transmissions the same as the KOP?

Please help if you can, we really want to move up a level for next year.