Lots do it - I don't. I don't have a great deal of faith in four small motor-mount bolts lifting the whole rear-end's weight.

 

Done it for years, didn't have a problem with this until I noticed the gap between the bumper and the tail pipe..
The mounts fail for other reasons too. When they do fail while jacking her up, they were probably about to fail anyway.

I'll continue to do it. It's not like they are that expensive to replace with 993 pieces.

 

So thats why my bumper to tailpipe gap is so wide!

 

993 mounts are not hydraulic as far as I know. And they are safe to jack from. 964 mounts will blow out.