I’ve been wondering about the A frame bushes from the beginning. It’s quite difficult to see wear on the two leg ends that are bolted to the chassis crossmember.
Quite often the rubber can just go soft without any actual wear being visible. This allows the axle to move laterally in relation to the chassis, and may well be the reason that you are getting two different measurements on each side of the vehicle. Having said that, I would only expect to find that effect when making loaded turns, unless it really knacker of course.