babak,
the 5 in the first line on your fender indicates that it was ordered ex-factory with a hardtop but without softtop. It is, however, not a "California Coupe", which - as Rodd described - is a 2 + 2.
The numbers in this line following the color codes can be
4 hardtop packed separate, with softtop on car
5 hardtop, no softtop
6 hardtop mounted, and softtop
7 "California Coupe"
The 4 at the end of the next line indicates "diplomat sales, NATO (military) sales, tourists (other than US-tourists) for delivery ex-factory", i.e. confirms your statement that the car was brought back to the US by a soldier.
Klaus
1969 280 SL