[quote=muddog321]InstaTrac (NV243 case or NP1) has 3 buttons. AutoTrac (NV246 case or NP8) has 4 buttons and clutch packs in the transfer case and is the only system for on pavement driving! Prior were the NV231 (87-93) lever and NP233 (94-97) electric motor. Your VIN # is the only sure way the dealer can get correct parts/listings!
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Great write up. Just to add the NP 233 was used as early as '92 on these trucks, mostly on the more equipped trucks, eg. the LT's and the SLT's.