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Two variants of the H-6 tanker have been noted: the HU-6 (or H-6U) PLAAF version, and the PLANAF's HU-6D (or H-6DU). These designations are uncertain, but for clarity we'll call them HU-6 and HU-6D. They can be distinguished by the HU-6 having a "solid" nose radome and the HU-6D retaining a "glass" nose with a chin radome. Observed serials for the HU-6 include 43595, 43698 and 43499. Ten HU-6s are thought to be assigned to the 8th Air Division (or possibly the 48th) at Leiyang Airbase in Guangzhou Military Region. The number and location of the HU-6Ds is uncertain but some sources mention them operating out of Lingshui (where the EP-3 landed in 2001!) on Hainan Island.

Turning to modifications, the "solid" nose and the removal of the chin radome in the PLAAF model appear to be related. The original '50s technology NAS-1 bomb-nav system with the old RBP-4 ground-mapping radar was replaced by a lighter, more modern navigation suite featuring dual INS, two "TACAN" (or possibly RSBN), and a weather radar in the nose. Besides saving weight this probably reduced drag somewhat and the weather radar - even without 360 degree coverage - could almost certainly be used in a ground mapping mode to aid navigation. Removing the PV-23 defensive fire control system would result in substantial weight savings, since the guns by themselves weigh 43kg apiece, never mind the turrets, sights, computer and attendant radar. One substantial difference from the Russian Tu-16 tankers is that while these employed either a unique wingtip-to-wingtip system or a single drogue from a hose-drum-unit in the bomb bay, the HU-6 tankers have two underwing pods. These were developed by the China Research Institute of Aero Accessories, and are common to both the PLAAF and PLANAF aircraft.

Although the guns have been removed it's been reported that a radar warning system and chaff/flare dispensers have been retained. This is an intelligent decision that should increase the aircraft's survivability in actual combat operations. As force multipliers tankers have long been high value assets - and thus high value targets - but provision for self protection by individual airplanes (beyond a coat of camouflage paint) have been slow in coming, at least in the USAF.

Removal of the fire control system would appear to render gunners superfluous, however it is likely that the gun positions in the aft fuselage are still manned by scanners to monitor the refueling. This is common practice in other air forces; for example, the Canadians add a scanner to the crew of their CC-130H(T)s for refueling sorties (required crew for such missions is pilot, copilot, navigator, flight engineer, loadmaster, and scanner). This supposition is supported by one photo of an HU-6D tanker that appears to show the silhouette of a crewmember in the tail gunner's position, and another that shows a line of HU-6s with six crewmen running towards each aircraft. Extrapolating from the bomber versions, these are probably pilot, copilot, navigator, flight engineer, radio operator, and scanner (it is likely that one of the last two is also tasked with operating the defensive systems). It also appears that the flight engineer has retained his dorsal bubble behind the cockpit. If the PLAAF and PLANAF still employ celestial navigation to back up the aircraft's electronic systems, the flight engineer is most likely the crewmember responsible for taking the navigator's sextant shots from that bubble.

Radio and light signals are reportedly available for the refueling itself, although it isn't clear precisely what these consist of. In photographs the signal lights on the A/R pods aren't visible, and since the photos were taken under bright day/VFR conditions other lighting isn't apparent, either. On most Western pods of this type the lights are red, yellow and green, and are often located behind a transparent panel below the opening for the drogue. However, at least one photo of a J-8D refueling simulator shows something above the pods that may be a light housing. Besides signal lights there is probably a system to illuminate portions of the airframe to give the receiver pilot a visual reference for A/R under low light conditions. The refueling-specific "radio signal" is something of a mystery, but may refer to a system whereby the receiver(s) can talk to the tanker crew "radio silent" (over the tanker's intercom) once plugged in to the drogue. For communications in general the aircraft is reported to have two VHF and two "frequency-hopping" (probably UHF) radios.