You must be remembering wrong, X517 (Mavic) wasn't in shops until 1998. The 217 had to have been released before that, it's predecessor and that wasn't in the shop until 1994. (some one will tell you if that's release date or model year, I have a feeling that's release date so add a year for model year.)
Most of this was (still is?) in the MOMBAT timeline and that based on very good evidence, just he often placed things on the release dates. Give or take a year but someone will know better.
Last year of Deore DX was 1993 (model)