Weld top rear strut / coil-over plate to rear cross member. Measure the top bushing on the coil-over. Use this measurement to locate and weld the other strut / coil-over plate to the side rail. Install the strut. Bolt the lower strut / coil-over mount to the strut with a piece of 7/8" dom as a spacer, 1-3/4" long. See diagram. Center the rear end housing under the frame. Using an angle finder on top of the housing, set it at 1 to 2 degrees up. Measure from a common point on the side rail to the housing on each side. These measurements are critical. Check and re-check them until they are perfect. Set the struts at a 20 degree angle using your angle finder. Tack the lower strut / coil-over mount to the housing. Finish lower coil over mount on housing. See diagram.
Assemble the rear hair pins the same way as you did the front ones. Install the rear bat wings and the 2 3/4" piece of dom to the hair pins. Set the bat wings the same distance from the end of the axle as the outside of the lower strut / coil-over mount. Locate the bushing end 3/4" out from the side rail, the same as you did with the front. Tack the bat wings to the rear end housing. Shape the hole in the outside hair pin plate to accept the dom tube. Making sure the plate is the same distance from the housing, tack it to the side rail. Shape the inside plate and tack it in place. Recheck all of your measurements and finish weld the hair pin and lower strut / coil- over mounts.