I'd balance type

Thanks for posting. This is a Coil Balance system--the spring within that housing is what regulates the opening and closing of the window. We can narrow this down even further for you, but we'll need more information. Can you remove the coil balance assembly, including the pivot shoe further down the track the coil attaches to? The identity of the pivot shoe will narrow down the kind of coil spring you need. This video below shows how to remove and replace coil balance assemblies.