16602 is a Single Hook design, while 16603 is a Double Hook design.
While the product is intended to be assembles outside the rifle and "drop-in" as one piece, because of variations in manufacturing - Kalashnikov Concern (formerly Izhmash) has repeatedly claimed that the majority of foreign manufacturers are producing AK type rifles without proper licensing, and quality control varies greatly - compatibility with your rifle can be confirmed by contacting the manufacturer - you can reach Tapco at 1-800-554-1445.
Mark H.