The full lock noise you are describing is when the full lock limit adjusters are pressed against the stopping point on the lower control arm. As the suspension moves it makes the limit adjuster rub against the stopper point on the control arm and you get that groaning/squeaking noise at full lock (Only at full lock, noises at any other point, I have no idea without seeing????).
When the cars were new the bolt head (limit adjuster) had a plastic/nylon cap on it and would not have made this noise. 20 or more years down the track it has probably been removed or fallen off on the road. So now you get metal on metal at full lock and a nice squeak or groan as the suspension moves .
My old Ke38 corolla did this too, a bit of a clean on the full lock limit adjuster points and a very light smear of grease stopped the noise for a long time better would be some new caps for the limit adjuster bolts, but I have never seen new ones.
Worth a try and very easy to do as a first option!