[75 911s]

I think you could do it without a drop. I just removed the cross bar off an engine out of the car, but I've also replaced the engine mounts while my other engine was in the car, but not the cross bar. Obviously you would have to remove the muffler, and the rear engine tin and support the engine.

I'm sure you've seen the self locking NUT hidden under each cross bar, and that you are not spinning the bolt in vain without holding the nut. I suppose that bolt could get bound up if the cross bar is getting bent.