The conning tower of Type 039A is similar to that of Type 039G, but the tower lacks the fin-shaped extrusion on the rear section of the conning towers of both the Type 039 and the Type 039G. Type 039AG: This second member of Type 039A series is frequently but erroneously identified as its development, Type 039B, because externally, the two version looks the same above waterline. The only difference lies below the waterline, which is not readily observed, and it's believed that all Type 039AG have been converted to Type 039B.