The NP231HD is built with every possible strength upgrade including all that is available through the aftermarket and original equipment manufacturer (NVG). We begin with a bare, empty case and fill it with new components consisting of the following:

• Wide chain (genuine Borg-Warner Morse)
• Wide-tooth main sprocket and front output shaft
• Heavy Duty SYE kit with 32 spline output shaft
• 6 pinion planetary gear set
• Choice of input gear spline (21, 23, 27, 29 or 32 spline)
• New bearings, seals, small parts, filter pickup, thrust washers, etc.
• No front driveshaft modifications are required: reuse existing front output yoke

The 231HD is a direct, bolt-in replacement for any Dodge or Jeep NP231 transfer case. Bolt patterns and shifting patterns are the same as your original unit. Vacuum actuated front axles are also accommodated.