The smaller plastic pulleys are problematic for all cars. I dont mean they wear out over night, but if you drive alot they will last a few months. They mainly just wear themselves out, they probably turn 2-3 times the revolutions as the ball diff pulleys. The ball diff pulleys see the same rocks, and dust the driver pulleys see, but because they are larger they do not wear out as quickly. I use the aluminum center pulleys, and believe it or not you can use 2 aluminums to replace the 2 plastic ones, That is if you dont want to use the one way pulley in combination with 1 aluminum pulley for full time 4wd.
All you do is slide 2 aluminum pulleys in place like the plastic ones did (side by side, set screws on opposite ends from each other) tighten the set screw like the aluminum holder did to hold the plastic pulleys in place on the shaft flat spot, Now you will need to tighten down the other aluminum pulley, But theres no flat spot? well tighten it down to make a mark on the shaft, then take the shaft out and make a flat spot with a file, or rotory tool. Put her back together, Now you have 2 aluminum pulleys, with out the one way for full time 4wd. This may not be allowed at a TCS even, but Tamiya should make a shaft with 2 flat spots to do this conversion. Mine sure have lasted a long time!
