This is a signed and stamped 16x20 of the famous piece by Jim Marshall - Johnny Cash (Flipping the Bird), San Quentin Prison, 1969; This is a silver gelatin photograph, and is very rare;  

I purchased this a few years back from a famous L.A. Movie Producer;  When he had Fahey Klein Gallery frame it, he chose to cover the signature and only have the image visible.  It can easily be reframed to show Jim Marshall's signature.  (see pics of the actual signature and Jim Marshall's writing on the left side)

 I'm moving and don't have room for any of my artwork unfortunately.  I have 3 pieces from Fahey Klein in Los Angeles and they can also confirm authenticity;  They did this in a  very high quality, solid wood frame;  

The whole piece measures 31" x 25" 

Thanks for looking.