I have two wagons that exhibit the same tendency to "lock" in the extreme left or right turn situation. I believe it is a result of the difference in the angle of the two tires when at the minimum turn radius locking the tires in that position. It appears that the inside tire is at almost 90 degrees to the vehicle which would make it almost impossible to return to straight ahead. I write it off as necessary to be able to turn such a large vehicle in such a short space.

My 83 tends to drift to the left, where the 85 stays straight and true on level roads. They do have different steering racks though. Neither car has anything but normal tire wear and I put on 200 miles per week on the 83. There are times when the 83 will not drift to the left and that is on roads that have a center crown to assist with drainage. Then the 83 just runs true until the crown disappears then drifts to the left. The 85 on same stretch with crown drifts right. As long as tire wear doesn't indicate a problem and the pull to the left is not difficult to control, don't worry about it.