Tech Note: JK gears are thicker than traditional Dana 44 gears and only work on 3.73 & Down carriers. JK gears have larger ring gear bolts than traditional Dana 44 gears. Carrier ring gear bolt holes may need to be drilled larger. Nitro gears are manufactured from 8620 steel gear forgings in the same manufacturing facilities as GM, Dodge, Ford & Toyota. They are precision machined using computer controlled processes, heat treated, CNC triple-lapped and Rockwell tested for hardness. These extra steps ensure excellent fitment, ideal contact pattern and smooth, quiet operation.