I don't know where that seller would of got that info from, there's a lot of conflicting information online for these basses and I can see an older advert also stating 65-68 but all the legit historys I've seen of Kay instruments don't back this up,the Teisco era kays do have serial numbers but I don't think they can be dated from them as they didn't keep records , a 1965 Kay would be a US made speed bump pickup bass and be worth closer to a grand , your bass is a Taiwanese made Teisco bass , I'm not trying to start an argument or rubbish your bass , looks great and a good price
I've got a 1938 Kay upright and a few 60s US Kay bass guitars and have geeked out on Kays for a while but if anyone had one back in the day or has any more info I'm happy to be proved wrong on this
https://en.m.wikipedia.org/wiki/Kay_Musical_Instrument_Company#:~:text=Early history (1890–1931),-Products by Stromberg&text=The Kay Musical Instrument Company,and renamed to Stromberg-Voisinet.
https://wesleyguitars.co.uk/2014/03/31/kay-k-20b-bass-guitar-short-scale-rickenbacker-4001-1970s-teisco/