All but a few of the old Marine SURC's used as training platforms are gone, they have been replaced by the RPB's - Navy version. SURC's are as good as gone (no sustainment funding) that is why they are used in training only roles.
USN CB-90's are HEAVILY modified and called the Riverine Command Boat (RCB) 5 of 6 have been received by RIVERINE's. RPB's are already at FOC, some new hulls will come in but as refresh's.
I belive the supported numbers are (24) RPB's, (12) RAB's and right now (6) RCB's, they are already at FOC, just waiting for a good CONOPs and employment.