"built motor" does not mean it has aftermarket rods, it just means that it is not the stock motor. there is no standard set in stone as far as i am concerned when somebody says built motor.
Pull the oil fill cap and see if it puffs smoke out of crankcase..... Maybe a piston???
We know the truck and what is done to it better then you guys and I would have no problems trying to help, I don't work that way I'd be more then willing to help you with any questions you guys have