Crosman model 101

Hi, I recently inherited from my dad a (what I believe to be) Crosman Model 101. Unbelievably, it holds air and shoots well. It may well have been 30 yrs since this was shot. I am just starting to look for general information about the gun. I understand serial numbers didn't come along for a number of years but 596D is stamped in the metal near the breech. Does that help identify the gun/history any? The gun also has a stamped Crosman logo on the side of the gun. I'd like to know more about this and can't seem to find much. Perhaps I'm missing something so I thought I'd ask.
I am going to shoot it a bit before really cleaning it up. I seem to remember dad telling me to not pump it more than 10x. Am I remembering him correctly? He was an avid shooter and this seems to be in excellent shape (no rust) so I may put off replacing the seals until I can learn a bit more about this gun.

Thank you very much!
 
Scope was added years ago but I do remember a small pinhole type sight that was removed. I imagine I'll find it in his shop soon enough. Thank you!

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