"First year model" (1979) so you have the curved rear fenders and the small metal gas tank?
Or do you have the large plastic tank and squared off rear fender/trunk lid (1980)
The changes happened in between so that is not 100% the way to determine year. The vin tag is on the steering neck, just like every other moped. It is only a 4 digit number because they only made them for a short run from spring 1979 to spring 1980.
Let me know the number when you find it