If ".349" refers to a specific file or version, it is likely an internal modding designation or a specific save file index used in custom installers for the "Burn" mod. Cash & Burn - GTA Wiki
For veteran players, the term "Burn" in the filename invokes the era of physical media. In the mid-2000s, it was common practice to "burn" GTA Vice City onto CD-Rs to create backups. During this process, errors often occurred. GTA Vice City - Burn -Setup-.349