According to the tech tip you need to relocate the 53 spring pivots and perches and make a plate similar to a lowering block to relocate the wheels in the center of the opening. You MUST have the pivot type perches. You
CANNOT weld your 40 perches solid to the 53 axle. You may want to PM Jim about this.
If you want to stay six lug, you need to find a complete rear end from a 48 and lower passenger car and swap the 53 third member into it.
Hope this clears things up a little bit.
