sent Caltrac pictures and awaiting reply..... they say the rear shackle is aftermarket and must be to lift the car up off the huge rear tires.... told me that on the phone when I was describing the set up to him. The springs are steel and not composite. They do come in two pieces and overlap at the axle...... some cars the springs are one piece. the drag links are the only question as if they are installed right.... the engineer at Caltrac says the angle of the rear shackles would be correct. He also says guys use this set up on the street all the time. More later.....