55.2-59 Rear axle center line

[iceman4]

I'm in the process of installing a 4 link suspension in my 57. Although logic would have the rear axle center line dead center of the factory bump stop location. I used the plum bob on my weighted axle level frame and have the center line 1" rearward of the center of the factory bump stop. I assume there is some forward and backward movement with the leaf spring shackles. Trying to decide if I should move it to center of bumpstop location or leave it 1" back ?