I can't say for sure without seeing it, but on my t-bird and mark viii, (both IRS, very similar to the 2015 mustang) I used to lift the rear from the rear differential mount - not from the diff itself, but from the giant bracket behind the diff.
Never had an issue doing it that way, but your car may be different.
Now for the 'don't lift from the pumpkin you'll ruin it' crowd to chime in.
I always cup the diff in the adapter on jack,guess I have been lucky. been doing it since 15 years old or 55 years and never caused a leak. as in everything else working on cars just pay attention and you will be fine. get in a hurrt and you will screw up something.
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