[sameyrasmea72]

I agree with the above, There is no way to know 100% for sure if the block is the original block. If the VO121TDJ matches the protectoplate, then that is about as close as you can get. If the VO121TDJ matches the protectoplate, the only way it would not be original was if the engine came out of a similarly cofigured truck built on the same day and same plant.