The J-8II was designed to perform as a high speed interceptor to counter enemy bomber fleets. With the introduction of the more modern Su-27/J-11/J-10, the PLAAF is moving the J-811 to a secondary role of "PGM Trucks" similar to the Q-5D/E modernization path.
Modification of the new J-8IIs include replacing the center fuselage "wet" drop-tank hardpoint with a weapons station and a newer "look-down/shoot-down" radar, similar to the KL-10, to provide secondary ground attack capability. This change will not only reduce the J-8II range but also impact its already poor aerodynamic performance. But, with the J-8II’s high-speed, it is expected to deliver the PGM payload quickly in any hit-and-run bombing exercise.
According to the latest rumor, the new G-modification will include the capability of launching two YJ-91 anti-radiation missiles in a SEAD (Suppression of Enemy Air Defense) role. It is not certain if the new G model will be a conversion from existing stock or a new factory build.
Just like the Q-5, the PLAAF is modeling its old fleet to get every last mile out of them.