It looks similar to the Sanden 508 mentioned in other threads. Do a google search for sanden 508 images and prices. 139 to more 249, make sure you get the correct pulley.

The symptoms seem a bit odd though. I'd be surprised if you could turn the compressor by hand with the clutch engaged yet the belt squealed and got hot and had a significant load on the engine. If the clutch isn't engaged and it's groaning/squealing then that part is definitely bad.