Ok, Here's my final determination with ya'lls help. Both of the injectors I have are the same size/length. In fact, the O-rings are the same size. As far as them being of the same manufacture, I'm not sure. One is labeled Denso while the other only has numbers and letters (N210H and LNP-057). The reason for the faulty injector: While I was in the process of installing all new seals I dropped one of them and didn't realize that the small needle broke. I found this out after starting the vehicle and had what sounded like a miss-fire, and then pulling all the injectors again. After ensuring same size and seal fitment I used the extra injector and viola! It works! The one question remains: Would any of you know if this injector is delivering the same amount of fuel as the origianls? I would assume so since they all came from a 6G72 motor but from a different vehicle and generally horsepower/torque come from the grind on the cam, not so much from the amount of fuel delivery