There has been speculation about the sole VS prefix recorded (VS 811119). I believe that is the only reference to a VS prefix, and your guess as to its authenticity is as good as mine. Someone here has seen it, and reported that does not look like a factory-applied SN. There is obviously some overlap between V-prefix frames and SV-prefix frames, and apparently some frames initially stamped with V-prefix SNs may have had the S added later. That's one reason that a VS-prefix is unlikely. The highest SV-prefix I have listed is SV8131xx, but I also show one having a slightly higher SN which is suspect. The lowest S-series I have listed is S8136xx. It would be nice to be able to fill in all the blanks regarding SNs of these. I have yet to see any data regarding how many SVs were military vs. post-war civilian. That information would also be interesting to establish.