Well apparently one piston or rod combo was a couple thou longer for some reason or other. Not sure exactly. 7 rods came out of the old motor. One of them was new. 6 of the Pistons were older. 2 of them were newer versions with coated skirts. All were previously used and given to me so who knows. I suppose I should consider myself lucky they were as close as they were. Everything I do is on a pretty meager car budget so, basically, you get what you pay for. My opinion is not to sweat the small stuff too much. I love a challenge like trying to build a rocket ship with a rock and two sticks.