Will a 1996 cadillac deville motor fit a 1999 cadillac deville?

I have a 1996 cadillac deville with a northstar motor and I have a 1999 cadillac deville with a northstar motor, if I want to put the 1996's motor into the 1999 cadillac will it fit? Will it totally be compatible? Both cars are automatic, V8's, and both have northstar engines.Will a 1996 cadillac deville motor fit a 1999 cadillac deville?You should be able to swap them out.Will a 1996 cadillac deville motor fit a 1999 cadillac deville?It would not be a legal swap since the donner engine is older. Emissions, you know so the EPA frowns on such things.