The first step is to take the front spring apart. Use some caution here. Some springs are under quite a bit of tension when they are in a pack. Clamp the spring with C-clamps and replace the center bolt with one about 3'' long. Now you can release the clamp slowly until the tension is relieved. Take the main leaf and install the shackles and spring perches. Lay this assembly out on a flat surface and measure the distance between the spring perches. This is the measurement you will use to locate the bat wings on the axle.
Lay the axle on its’ face and level the king pin boss. Use shims if necessary to keep the axle level. Find the center of the axle and lay out the bat wing location using the spring perch measurement. Run two bolts through the holes for the clevis' and nut them. Using an angle finder across the bolts, set them at 5 degrees down at the top. Holding the bat wings at a 90 degree from the axle, tack them in place. Re-check your measurements and angles and finish weld the bat wings to the axle.