Will the motor out of 95 monte carlo ls replace the motor in a 97 z34?

You would need way more than Steven said. So no. Don't use it.

Since they are not both 3.4 engines, you could have a bunch of changes to make, including the engine computer.
The exhaust, cooling, and motor mounts would probably be different too.
So the engine would fit since both cars used both engines, but it could be a major project to get it to run.

Since they are not both 3.4 engines, you could have a bunch of changes to make, including the engine computer.
The exhaust, cooling, and motor mounts would probably be different too.
So the engine would fit since both cars used both engines, but it could be a major project to get it to run.