Are stock rear (52\") springs symmetrical? Are they made to the same dimensions for a K5, K10, and K20? Is the centering pin centered between the spring eyes? Is there a "front" and "rear" when installing them? I always thought that they were centered, so there wouldn't be a "front eye" and "rear eye", but my friend claims that the centering pin is 1 1/2" more toward the front of his spring pack.