The car would have to sit on it's wheels not to block rotation but to ensure the correct length of the shaft when the rear suspension is loaded considering it is pivoting about the trunk mount. When I removed my 3.27 diff from the donor the rear axle was moving without the shaft. I got it from many posts here on the forum, the BBB doesn't say anything and I would not have done that, it was a PITA. I guess that if you don't split the shaft then you don't have to do it.