Not as a regular production gun.
They did have an engraving custom shop for a little while and it could have been done there,,, or someone had one done outside the factory. Without digging into the books,,, I think there may have been a few specials done to be used as auction pieces for big charaties.
Ruger did have the "Studio of Art and Decoration", but I don't think that had begun as early as 1999. The only way to tell for sure is to give Ruger a call and see if your gun was engraved, or if it looks to the Ruger gals like it was just a normal MK4-50 with a normal price tag and went to a normal distributor with a bunch of others that were also just as normal.