What pill has M363 on it?

It's generic for norco or vicodin

It has 10mg hyrdrocodone with 325mg acetaminophen in it.

One more popular brand name is Lortab. They often add some numbers to the name to determine the strength of a pill. In this case, it can be Lortab 10/325, or Norco 10/325, or Vicodin 10/325.