I too am a Ruvalcaba. My family is also from Yahualica. My great-grandfather was Refugio (sp?) Ruvalcaba. I know that the Ruvalcabas came from Northern Spain, but that the surname is believed to be Moorish, originally. My dad has more of the family history, including a family tree, but I'm not sure how far back it goes. Also, I have an image of the Ruvalcaba coat-of-arms, if anyone is interested. I will describe it briefly in case the image doesn't come out well: 5 red stars over a green oak tree, with two silver wolves on either side of the tree. The version in the attachment (sent recently from my cousin) is slightly different than the one I had been familiar with. This one shows the wolves both facing the same direction. The one that I had seen before has the wolves both facing the tree. I don't know which one is correct. I sent the link to this page to my parents. Hopefully they can provide a more complete family history.
Incidentally, my branch of the family has a tradition of giving babies "R" names. Is this true for any of you?