Yeah, you are probably right. I think my fixation was due to knowing someone that did it on a 2 post lift and the car was either really hard to get good door gaps or impossible to do (can't remember which). I know they welded a bow into the car, that I am certain of.
I think the difference is that the factory didn't weld it all together with a drivetrain in the car. Hanging a motor and rear axle past the points of support on the chassis will put the car into a state different than the factory had it when they welded it all together.
But in retrospect, jack stands will give a better datum for the chassis than supporting it on the suspension.
At the very least, if someone was looking for perfection and didn't have the drivetrain out of the car, I think they need to support the car at 4 points. One set just in front of the trans crossmember, one set at the front of the rear frame horns and one set at both the front and rear bumper mounts. And those points need to be measured to match the below image.
View attachment 1716332321
In theory, that would put the chassis in an "as factory" condition.
What if they design things so that whatever flex the chassis had when it was complete and sitting on the suspension would set the gaps to where they wanted them? If so, that would be the state I would want to fix the chassis at. Kind of a long shot that they would be able to plan ahead for that though.
at if they design things so that whatever flex the chassis had when it was complete and sitting on the suspension would set the gaps to where they wanted them? If so, that would be the state I would want to fix the chassis at. Kind of a long shot that they would be able to plan ahead for that thoug