Tom,
I don't know if Airstream ever completely addressed the issue. I have a 1975 rear bath Sovereign, it has sag and seperation. The axles are okay, but will need replacing eventually. The biggest problem with it was hidden damage at the main frame attachment point at the front A-frame. A water leak had rotted the floor out under the C-channel and caused the main hold down bolts to fail. I missed this one on the intial inspection. It caused quite a bit of interior mayhem that I attributed to bad balance and axles. I have a 1980 31' Excella, no signs of sag, but the rear floor is rotted out along with some floor and a frame outrigger at the front right side just forward of the door. It was caused by an unrepaired leak. And the axles are toast and will have to be replaced before it gets towed very far. Neither one of my units received the best of care over the years, whether from ingnorance or lack of caring, I don't know but they are still quality units that can and will be rebuilt. Your best bet might be to either plan on the repairs or buy a already repaired unit. Hopefully one that has been repaired by someone that knew what they were doing. I would run down some posts by StingrayL82, he had his 70's Vintage unit completely rebuilt. It was a bit pricey but a whole lot less than a brand new unit. And he was very happy with the end result.
Aaron
