Can anyone tell me what is the diff between the 5.9 gas light duty motor and the heavy duty 5.9 THE vin decode has a Z for the light duty and a 5 for the heavy duty No one around here can tell me what the diff is I want to rebuild a replacement motor for my truck it has the light duty motor can the heavy duty replace the light duty with no problems ???????

 

Pretty sure the motor is exactly the same, check this out.

https://dodgeforum.com/forum/2nd-gen...eavy-duty.html