Identifying Vintage Guitars, Banjos Mandolins exceptions to every rule and the following is only a general guide for identifying Gibson "A" Style mandolins.. - What kind of guitar is it? How old is it? What 's it worth? What is this stupid thing? I know I hear questions like this several times a day,. - I am trying to identify an old guitar I inherited from my grandmother. One of the guys in repairs at McCabe 's in LA thought it might be an old .