Take the OE panhard out, measure center to center distance and adjust your "triple" adjustable bar to match. Put it in and lower your car off the lift/jackstands. Remember to not support the car under the rear axle, let the axle drop down. It's easier to take the wheels/tires off the car when you do this but you can keep them.
After putting the adjustable bar in, lower your car so the chassis is loaded...........roll it 15/20' and back to set the chassis. Put plumb bobs down each side of the rear quarter panel, make sure the strings pass through the center of the wheel. Measure both sides, subtract the larger number for the smaller number and divide by two. This will give you the amount and direction you need to move the rearend to get it centered under the car. Spec is to have both sides within 1/8" of each other or closer. Each time you adjust the "triple" adjustable bar you need to lower the car and roll it out and back in to set the chassis, and also recheck the measurements to make sure nothing has moved. If all is Ok, put locktite on the threads and torque the nuts down. It is always prudent to take a permanent marker and mark the flats of the lock nuts and extend the line to the panhard bar. This way you can see if anything changes..................just something I've always done in 35+ years of racing..........safety first!