Late Omega speedmaster tritium serial number range

Hello,

I've found a good looking tritium speedmaster for sale that I am going to see tomorrow.

According to the seller it is a 3570.50 with a 4835xxxx serial number which would date it to 1998 but to my understanding last tritium Speedmaster were from 1997. It is powered by a yellow gold 861 movement with matching serial. Is it consistent ? I believe that serial number datation is more of a ballpark than an accurate assessment but Id prefer to be sure.


Thanks for your help !

It was almost perfect but a white stain on the dial prevented me from buying it. It's sad but I wouldn't have been able to unsee it once worn.
I guess that's part of the thrill of looking for the perfect watch !

In any case thanks for your help !