Will a BUICK regal motor fit a Nissan Altima
Anything can be made to fit anything. The question is how much time/trouble/money is it worth to fit a Buick motor into a Nissan. You'll have to adapt/modify or make your own wiring harness. None of the Buicks sending units will work with your Nissan gauges/modules. You'll have to use the Buick's tranny, and that will have to be adapted to work with the Nissan drive train and shift linkages. And if you change the weight of the vehicle enough, your suspension and brakes will be out of balance.
Search Buick Regal Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Buick Regal Experts