If your wanting to redrill the center bolt hole, the spring leafs are hardened. They need to be drilled with good bits, lots of cutting oil at a slow pace. You will probably want to pull the spring packs apart and drill on a press, and then your probably only going to want to relocate the main leaf center hole, and shift the other springs to the new hole. Watch the length of the 2nd leaf that its not too long. The end can be cut off with a cutoff wheel and debured. Gene