It has a serial number beginning with 58******. Am I right in assuming that this is from 1998, or not? Genuine watch but no original cards!
Yes, seems to be 1998. See here: https://est1897.co.uk/omega-serial-numbers-how-old-is-your-omega-watch
You really can't rely on those online tables, during certain periods they are way off. Auto SMP numbers jump from 60m to 80m during the 2000-2002 period and Speedmasters have stayed in the 77-78m range for the past 10 years. In addition, the quartz numbers often don't run alongside the autos. That said, based on a few SMPs that have passed through my hands, I would say that watch likely is indeed from 1998-99
Great choice. That my was my first Omega back in 2002. It’s the only one that’s been with me this long. Love the 2264.