50 Inch Axle Spacing - Current Production
Late Production - 1 3/4 Inch end holes on PL-1 and 1 3/4 Inch end holes on PL-2 or 3
Use pair codes to identify springs that are similar except for the U-bolt Plate (JP)
Noncurrent (NC) production use square bend U-Bolts with a spring steel U-Bolt Plate (JP)
Current (C) production springs use semi-round bend U-bolts with a cast U-bolt plate
Conversion to current production design springs is recommended to improve spring clamping