I agree--the 19 4 option generally associates with our 1940 option. However, you may want to double check, just in case. It couldn't hurt. The 1940 can support a window sash weight range of 14 through 17 pounds.
Please keep in mind that the weight range information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate.