Cheers FluffyChicken, I'd forgotten about that resource, exceptional piece of work.As above.
I'll also drop this link here.
https://www.retrobike.co.uk/threads...model-number-to-model-years-1980-1999.439341/And search the model from the 'find on page' from your browser.
And this one too.
https://www.retrobike.co.uk/threads/shimano-groupsets-years-and-m-numbers.439342/
And then double check it with the catalogue.
https://www.retrobike.co.uk/threads/shimano-product-catalogues-sti-tech-info.450253/