How to find exact datasheet of an Op-Amp from the IC markings?
741D is a variant of the 741, you would need to read the manufacturer's own datasheet to find what the D signifies, but it is probably the package (e.g. plastic 8-pin DIP as opposed to ceramic DIP or SOIC). 

However there is a chance that it is a variant in supply voltage range or some other parameter like input offset voltage, so that is worth checking if performance is critical. But for most parameters, any 741 datasheet will do including LM741 or the original uA741 if you can find it.

And JRC is a well known manufacturer so their databook or website would be the place to start. A little searching shows some company reorganisation so this is the site you need for their semiconductors, rather than the obvious one. Searching that page for 741 yields several hits including this: where you can download a datasheet. And that shows a DIP - NJM741D and a SOIC - NJM741M. 

8001 is most likely to be a date code : week 1 of 1980. That would be before the reorganisation hence the manufacturer is JRC rather than NJM.