I have never been to Iowa City. However, my '87 300D has been across South Dakota, Nebraska, Montana, Wyoming, Utah, Idaho, and other states where it can be VERY windy. On a trip last summer my '87 300D (W124 chassis) was VERY difficult to keep in lane. When I returned home to Tennessee I spend the next few months trying to find out why. I went to the DEALER for an alignment and they fixed front toe-in.
I have heard that W124's and W126's are sensitive to winds. This is generally from people who have the problem and "live with it". However, others have had NO problems and they say they are not sidewind sensitive.
I have also changed the steering box beacuse mine was previously adjusted TOO TIGHT. IF its loose, then it CAN be tightened with good results. Just make sure to leave 10-25 mm of play. Without play the box will be damaged.
I've replaced the gearbox on my '87 300D after it was diagnosed too tight. On the straight six diesel, it was easy, nothing in the way. Just needed a Pitman arm puller & snap ring pliers to get the circlip on/off that goes over the Pitman arm. No alignment is needed. On the straight six diesel, there was no exhaust, etc to get in my way.