I am installing a 4-link into a 66 Mustang Coupe. I put a Mustang II into the car. Plus i dont want to measure 108 from the front. Its sitting on Jack stands. I have put a plumb bob like you did but, its to off. I need measurement of the aft old leak spring perch mounts to housing center. I know this point is square and equal. Please give me any measurement you have thats helped.