Eddie Van Halen & Alex Van Halen - 'Unfinished/Between Us Two' - Full Song
The song doesn't need vocals at all and maybe it was written in that vein. I've seen old online articles (well, message board posts) about the track that note Sammy Hagar had written some words for the music but they were scrapped. This just doesn't seem like a song that needs words to me.
The part starting at 4:15 is just so good when it comes to guitar work - all those classic Eddie Van Halen signatures are there. One note and you know who is playing.
Knowing that this track is the end really hits home and makes it all the more haunting.