Help finding an obscure old b-side
 

I know it's a long shot, but I have been trying to figure it out for a long time now and I have had 0 luck.
Some time between the mid 80s, and the mid 90s I had a cassette tape from some punk band where the final track on B side of the tape was them playing a classical song. I'm not sure who the band was, and I am not sure if it was Mozart, Beethoven, or Bach (100% sure it was one of those 3). I believe it was a sonata and it was in C.
I will know it immediately if I hear it. Any help would be greatly appreciated.