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Anyone know the difference between an NP 231J and a NP 231D? I know that the J is for Jeep and the D is for Dodge, and that there's a C one for Chevy, but what are the physical differences


Mounting flanges are sifferent, Input shafts are different (length, and spline). D HD, and C HD units have 6 pinion planataries, and 2 inch wide chains. (none HD units have smaller chain, and only 3 planet gears.

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can I use a SYE kit for a J on a D case?


Prob so. I used a "J" kit on my CHD unit. The SYE components replace the Mainshaft, tailhousing, and rear yoke with a fixed yoke obviously. The entire transfer case has to come apart, but it's not too involved.

One thing to consider is that the SYE units only offer cable drive speedo's and if you have a VSS back there now, it's a goner. (Unless you machine the gear off, and press fit a reluctor ring on it or something like that)

87 Raider 4D56td v5MT1
31's..Basically Stock