IIRC only the 60 or so KC10s have a centreline hose. The boom on the KC135, and I assume any other boom tanker, can be fitted with a Boom Drogue Adapter. But if you are using a USAF tanker why not use the boom directly. The KC130 tankers have probe and drogue wing pods, so it would be a tad interesting refuelling a P8 from them.