1 Ball bearing installed level winder tube kit removes friction and add casting distance. You use original worm shaft. 4 models, 2500, 4000, 5000, 6000 available for ABU 2500/3500C, 4000-4600, 5000-5600, 6000-6600 respectively. Sorry but 1500 for ABU1500C is no longer in production since around 2005.