Che Guevara seems to have always had a Parker 51 in his pocket. This picture is one of the clearer ones showing the iconic Parker clip
A Parker fountain pen is also described as being among his (looted) personal effects when he was captured and executed. The pen, if it still exists, will now be in the hands of some Bolivian soldier, or his antecedent. Unlike el che's wristwatch, which was kept as a trophy, and worn for many years by the CIA agent present when he died.