Originally Posted by Gydyup
May not be in the rear, maybe off in front, causing the the corresponding droop in the rear.
Very true! He should also consider checking the distance from the "snubbers" or "jounce kits" to the corresponding metal contact surface an all 4 corners to help determine if the problem lies in the suspension or the body mounts/unibody. This may not work in the rear if the spring rate is soft enough that unibody twist(if any) may cause deflection in the springs. Measuring distances from wheelhouse arches to the ground CANNOT be trusted for "for sure" test results, although it can get you in the ballpark.
All of these checks should be done on an alignment rack in the presence of a well-trained technician at which time he should be able to easily determine the root of the problem. I have seen SO MANY people chase their tails on problems like this when it ended up being wasted front end parts, improper tire pressure, bad alignment(which can cause this by itself), etc. Also, "Real" alignment technicians are VERY VERY hard to find these days! Most guys just put measurements "in the green" not knowing why or the ramifications of such actions.
Ask me if needed, I averaged 8-10 alignments a day while a technician at Firestone and have been in the presence of guys like this.