Yes.
Sure, its the sameengine
Yes.
1996
Yes. You'll need to change the exhaust and cooling systems.
Why cant you put any 5.0 engine in your 1991 mercury grand marquis
No.
With $$$ anything you want.
I doubt it very much as they change engine specs every year.
no
5
no
If you have enough money and skill you can put about any engine in any car.