If you google the part number for the PreFL exhaust OCV assy, the first hit is Amayama, another genuine parts vendor I forgot to mention in your FB post.
Since only a single part is listed, you can be sure it fits both banks of cylinders.
Individual part numbers for the assy are not listed eg the solenoid and the housings internal oil filter. I’d recommend also getting the gasket for the assy but you might get away with reusing yours.
https://www.amayama.com/en/part/subaru/ ... 0/diagramsIt’s expensive to replace all OCV’s so I’d recommend datalogging the fault mode since the originating cause might be related to incorrect reassembly after service, eg a timing belt job, blocked oil filters or galled OCV (covered by replacing the OCV assy), sludged or FOD damaged cam sprocket or a harness, harness plug or ecu fault (in some cases deriving from oil contamination of the harness).
It really depends on the driving symptoms, service history of the car, the VVT angle behaviour in logging, mileage related wear and tear, the engine diagnostic trouble codes (DTC’s) but real mechanics diagnose first before parts swapping.
AVCs diagnostics:
viewtopic.php?t=36504FSM & parts faq:
viewtopic.php?f=6&t=34980