ARP

1/2 Inch - 20 Thread Size; 3.470 Inch Under Head Length; 12 Point Style Head For Aftermarket Axles

1/2 Inch - 20 Thread Size; 3.125 Inch Under Head Length; 0.400 Inch Knurl Length; Chrysler Rear

7/16 Inch - 20 Thread Size; 3.165 Inch Under Head Length; 0.420 Inch Knurl Length; Late GM Drum Brake

7/16 Inch - 20 Thread Size; 3.200 Inch Under Head Length; 0.300 Inch Knurl Length; Late GM Disc Brake and Early GM Drum Brake