I agree, our state title has a provision for the VIN only, so the motor number would go in the VIN location on the title.
Unless your "new" truck's former title (perhaps from another state) has the "Unit serial number" off the door plate as the VIN (for example: H54F005877). Then, your state will get very mixed up if your former title (which often has to be surrendered) has a different number from the engine number (that you will try to use as a VIN on the application).
In Louisiana, for example, the DMV site states that you would have to provide "The Certificate of Title or manufacturer's certificate of origin, for antique or custom vehicles that have already been titled"; and, (among other things) you would also have to provide "A physical inspection report by the Louisiana State Police Troop".
If your original title used the door-plate Unit serial number (as I have shown above) and your Vehicle Application Form has the Engine serial number as the VIN, the State Trooper would would most likely get a little confused.
