C-97G 53-0106 seen here in August 1971 had finally lost all its KC-97 attributes (see previous picture). 
It had undergone modifications and was renamed RIVET STOCK.
Its primary mission was then targeting the SA-4 system.
<br /><br />
<small>The Big Safari program name mentioned corresponds to the period when 
the aircraft was photographed. The aircraft modifications and the Big Safari 
program in which this particular aircraft was involved were not necessarily 
the same before or after.</small>