Strange Engineering only uses the highest quality gears available from U.S. Gear, Motive Gear and Dana/Spicer. The 8620 pro street gears provide excellent life for circle track, street and some drag race applications. The 9310 pro gears are designed drag racing only and absorb high impact shock loads that occur in straight line racing applications. When investing in a new ring and pinion, it is important to use new bearings, seals, ring gear bolts and other essential installation components. Strange offers a wide selection of installation kits to compliment the line of gears.