Originally posted by freelancefool
You don't use that to adjust toe. You would use them to adjust rear caster. The big benefit would be the heim joints instead of the urethane bushings. It should give you a much tighter suspension setup because it will reduce flex even further. If you need to adjust read to you use the toe adjustment control arm. It's the only lower control arm on the rear of the car with a ball joint.

you can see how extending or shortening the length of the trailing arm would change some geometry that our rear suspension is not technically allowed for. I just googled rear caster and found a couple things mentioning it but I have never heard of it being an area of concern.

In theory if urethane bushings were used in the rear and the addition of the adjustable trailing arms with a non-oem length you could assume some degree of stress on the lower control arms due to misalignment. The lower arm mounts to the knuckle without a ball joint.