That's right boys and girls. For the first time in its history, there is now a choice of ratios for the Rockwell 2.5 Ton Axle. Pinion gears are crafted from 9310 alloy with the "ring" gear made from 8620 alloy. Both pieces are shot peened for added strength. The 4.90:1 set includes a new aircraft grade 4340 input shaft. Gears are spiral cut and lapped for a perfect matching fit.