Thanks to everyone for the replies. I did remove the exhaust. There is nothing blocking, but it has zero free play front to back. I had to squeeze a prybar in between the rear flange and the diff to get any space at all and it's not enough. I agree that it seems the driveshaft was produced slightly too long. I have no idea how the previous owner got it in there unless geometry has changed slightly. This car has some rear left side damage due to a run in with a guard rail. There's nothing obvious wrong with the subframe, but the left rear wheel was bent a bit at the top.