In 2005, I believe we used 80/20 linear bearings. We never had a problem with them binding, even with the tetra up 12 feet pulling on our bearings. I can't get you part numbers now, but I might remember to come back and get you them.
We found that the rail they slide on is very, very heavy, especially for the "light-weight" game of 2007.
Each peice we used was over 5 pounds.
We're planning to use a similar system to lift tubes this year. We have plans to improve on it, and to make it much faster (full travel in less than one second (/me crosses fingers)) and lighter. We're only moving a pound of tube
