Can you put a husqvanna bar on a poulan chainsaw as long as its the same size?

As log as it fits to the motor and bolts up correctly, it might work ok. You can put a Husqvarna bar on a Johnsred. I kinda doubt a Husq. will fit on a Poulan but hey, no harm in giving it a try. Keep in mind, the chain will have to be the same to work on the pulley otherwise, it will not work correctly. You do not want to mess up what you already have.