Checking the year of manufacture on an old Jubilee?

[TeeBee97]

Hello all!

I'm very interested in buying an old 1601 Datejust from -66. It's on a folded jubilee bracelet, which should be 6251 (I haven't asked the seller yet) but its endlinks are "55" which is correct.

However, in order to make sure that the bracelet could be original, I'm very keen on knowing the date of manufacture - is this something that's stamped onto old jubilee clasps? It would be great to know when it's made...

From what I've read Rolex started stamping the year of manufacture in 1976, but I've also read that you can check the year of manufacture on bracelets older than that. Therefore I'm asking you guys.

Thank you for your help, it's truly appreciated!

//Teodor