These drivers don't use the lugs outside the rails. Some of the new tracks don't even have them there anymore. The drive shaft is also easier to install. They are .25" smaller in diameter than the molded ones. They run smoother and don't have to wear in to fit. All shaft sizes are available. The price is for a single driver. Specify your shaft size.
AVID PRODUCTS 2.86" & 3" PITCH FOR HEX SHAFTS