Dodge Repair: 2002 ram 4.7ltr, camshaft position sensor, right cylinder

Question
replaced 2002 ram 1500 4.7ltr with a 2007 dakota 4.7ltr was told they are interchangable, however when i try to fire it up 2 cylinders fire then the computer shuts it down before a full start.  where am i going wrong or are these two engines not compatible? very frustrated please help

Answer
The 2002 and 2007 4.7l engine are not directly interchangable. Although they same many of the same parts, two of the most important one are year specefic. Those being the camshaft on the right cylinder head and the crankshaft. Those shafts have trigger wheels on them that the camshaft position sensor and the crankshat position sensor read and send information back to the PCM so it knows when to pulse the injectors and fire the spark plug coils. If the signals are wrong the engine will not fire. There is no easy fix for this like changing out the 2002 computer for a 2007 computer, they are also not intercangable on the vehicle.