The Dana 30 is the OEM rear end. I just mentioned it in case it meant anything to anyone. Some rear ends have an offset to one side although i don't know that this one has that. There is a lot less drive shaft clearance on the passengers side of the car than on the drivers side tho. I tend to agree that its probably a spring/suspension problem tho. I think it squats way too much under acceleration. The more I look at the car tho the more i think it IS sagging in the rear. Here again I don't know if its the suspension or if the Chevy engine just doesn't weight as much as the Volvo engine did which would cause the front end of the car to not sit as low as it should.
BTW the car is a 265 (2 series, 6 cylinder, 5 doors) which is a station wagon so it already has station wagon springs under it. They could be old and saggy tho never know.