I was told to get a big piece of cardboard to map out a 4 link, 3Ft.x5Ft or longer and measure the hieght and center to center distances on the rear end brackets on both sides and the same on the front mounting holes on the frame, chassis and use the ground as a baseline measuring point. Once that was transferred onto the cardboard make lines from the holes on the rear end to each hole on the chassis and shoot for a intercexting point around 7 inches up from the ground and 51 inches from the centers of the holes on the rear end brackets as a staring point an a 3200 Lb car with 500 HP and a automatic with a trans brake that would run in the mid tens to mid elevens in the 1/4 mile. I was told later to make sure the rear end brackets holes, if not directly above the axle center line should be extended to where they would be directly above the center of the rear end housing The car I treid using that on was 1963 or 1964 Nova with a 585 HP SB Chevy with a turbo 400 in it and a early TCI converter, That car as a slug, it struggle to run mid elevens at the old LACR drag strip It didn't spin the tires ever, it had really big set of M/T ET Street tires, maybe 15x33x15 on 14 inch wide rims We move the intercexting points from 48 inches out and 6 inches up to 53 inches out and 5 inches up, no measureable changes in 60 ft. times or reaction times Maybe we didn't make a big enough change, the owner got discourage and gave up trying to make the car better, it was a Pro Street car that he spent a bunch of money and time on to make it real nice, it was really nice It just didn't run as fast as he wanted