Aside from the obvious change of the HQ-7 to the HQ-16 and VLS, the Type 1130 CIWS over the AK630, and the YJ-83 to the YJ-12, the change of equipment as follows.
Type 360 search radar to the Type 382 search radar.
Type 381 search radar to the Type 364 surface search radar.
This is interesting because the Type 051B is the test bed for the Type 381 radar which is the first frequency scan PAR used in the PLAN. The experience from the Type 381 combined with the Fregat Top Plate array on the Sovremenny merges to make the Type 382.
As a note, on the 051B, the Type 382 is not placed with the Type 381 is. This is strangely unlike that of the 051C, where the fore is the Type 364 radar, and the back is the Top Plate. On the 051B refit, the order is reversed with the Type 382 on front and 364 on the back, like the Type 054A, with this template originally set by the 052B.
Less noticeable is that the ESM and ECM fit of the 051B is taken from the 052D, despite the radar and SAM layout being taken from the 054A. That means the 726-1 and 726-2 ESM, 726-3 ECM, and 726-4 Decoy.