From what I gather, they were made somewhere between 1959 and 1967. No "A" suffix has been seen that I know of, I do believe there may be a no-suffix version. The "B" series is very uncommon, the "C" series is the most common M59, but in contrast to M59/66 production, the M59 overall is a very low production model.
Okay, I really like this rifle with the "battle-worn" look but I gotta know. What the heck is the object in the leather pouch in the first two photos?
That is a Yugoslavian oiler, there is two type slings as well, the leather and a fabric sling, leather is most common associated with the M59.