1st,2nd and 3rd gear rotate on caged needle roller bearing's using your stock gear's. Rollerizing the gears's will reduce your rotating friction and increase your horsepower. The rollerized main shaft is 1.3 lbs. lighter than the stock T-10 main shaft. We also offer ,as an option, a gundrilled main shaft that will save you 2.2 lbs. more of rotating weight. Field testing with the rollerized main shaft has proven an increase in horsepower to the rear wheels.