The 194 3.1 only
3.4, and 3.8.
GM L82 3.1L V6
yes
Yes
yes it will fit
YES, They are the same engines. That would be a direct bolt in.
No, they are 2 totally different bodystyles
No, the compressors and mounting points are different on the 95 Lumina
Yes
No, there is no information suggests that a 1996 Buick Century 231 will fit into a 1999 Chevy Lumina.
No, Chevy Lumina Z34 ever came with a 3.7L engine. So probably not.....
YES. Those 2 engines are the same. NO difference. It is a direct bolt in.