I have posted a few times over the past year on this subject and have gotten some very good info. Now, after almost a year of dealing with this problem, I finally have an answer as to what is causing the pull. A little back history:

The car was in a front-end collision in the Spring of 2010. The damage was isolated to the sheet metal forward of the strut towers and I was able to drive the car home after the collision without feeling any difference. In taking the front end apart, I found the inner fenders pushed slightly to the right. I believed the car was salvageable, so I had a local frame shop pull the metal straight.

The front suspension of my 84 240 was rebuilt with new strut inserts, mounts and ball joints at the end of May 2011. The car was given an alignment and returned; it went down the road perfectly. Late in the summer of 2011, the car began pulling left. I took it back to the alignment shop and they found a blown rack boot and a worn inner tie rod. I then replaced the steering rack and outer tie rod ends. The car was realigned and returned as "fixed". The pull remained. For the next six months, the 240 was in and out of the shop checking tires, bushings (all control arm bushings are tight and i personally verified this with the car on a lift) and all the previously completed work with no change.

I finally took the car to a different alignment shop where they found a disturbing caster split. When the car was aligned after the struts, the caster value was 2.3 degrees left and 2.9 degrees right. On the last alignment, the left value had decreased to 1.5 degrees and the right remained at 2.9 degrees. The current cross-caster value on the car is 1.5 degrees, obviously pulling the car left.

Now my questions: Are there anything that would cause a loss of caster over the course of a year beside frame damage? Should I be worried about the structural rigidity of the from end?

Thanks,
Nick