It’s kind of a “Ship of Theseus” problem. If all of the components can be traced back to a single year of manufacture, then, yes. Or, you could say the year of the bass is the year it was assembled. I don’t know how this could be verified, though. You could say the year of the bass is the year of its youngest component. Going further, you could count some components as less significant than others. Then you can say the year of the bass is the year of its youngest significant component. Say everything was made in 1977, except the tone cap was replaced in 1998. Are you going to say the bass is a 1998? No. Who cares when the tone cap was made?
This gets even more muddy with bolt-on instruments. If a neck-through body/neck was made in 1969 (like this empty shell of a Rick with a cracked neck for $3500 https://reverb.com/item/61274871-rare-1969-lefty-rickenbacker-4001-bass-original-mapleglo-w-checkerboard-binding-restoration-project
), you would probably call it a ‘69, regardless of the electronics. But the neck and body are significant components by any standard. What if the body and neck were made in different years? You would probably ignore a re-fret, but if the frets are original and in good shape, that would be bonus points for that year, right?It’s a deep philosophical question and I have had a fair amount of beer so I feel like I have said a lot of words and did not answer the question and now understand why I don’t get invited to parties.