The Block 152 Pavehawk upgrades are actually a series of upgrades and they're still being done. Think of it as Block 152A, Block 152B, etc... I think we're on the 4th one now. A few birds, primarily 422TES birds at Nellis AFB, even have the Block 162 upgrade. This one mounts the radar higher and in the middle of the nose. A lot of the Block 152 series of upgrades are not readily apparent externally as they concern Com, Nav, and other upgrades but some are visible. The first thing was to add two chaff and flare boxes to the each side of the tail boom instead of one per side. The AN/AAR-47 Missile Warning Receiver's plume detectors were added. Two in a fairing on the aft center of the vertical tail fin, and one on each main gear sponson (this also mandated the move of the port and starboard position lights up on the ESSS fairings-since ESSS is NEVER used on Pavehawks). The latest Block 152 upgrade moves the forward plume detectors from the main gear sponsons, on to the upper nose canted outwards just like on the MH-60's of the 160th SOAR birds. This also added a chaff/flare box (usually flares) on each main gear sponson where the plume detectors used to be. I might also add that while the ALE-40/47 chaff/flare boxes used to be used (rectangular black box), we've now switched to primarily using the M-130 chaff/flare boxes (more box shaped and usually gray). The M-130 gives you more countermeasures per dispenser (more flares and chaff bundles). On the main gear sponsons the ALE-40/47 fired straight down, and the new M-130's fire canted forward and canted out to the side, and can actually be adjusted to fire at a given angle. Along with the addition of the AN/AAR system, an "Oh Sh!!" button was mounted on the upper cabin framework just aft of the gunner's and FE's position. This allows anyone in the rear of the HH-60G to respond to a sighting of a missile launch by hitting the button and launching flares/chaff. You'll also note that at one point during the Block 152 upgrades, the flush mounted VHF/FM antenna on the leading edge of the vertical tail was deleted along with the VHF/FM homing antennas located aft of the pilot and co-pilot's doors (black vertical towel rack looking antenna). These were deleted due to the instalation of a new VHF-AM/FM whip antenna on top of the vertical tail, and is easily distinguishable due to the lack of black paint on the forward leading edge of the vertical fin (even though some of the fin leading edges are still painted black even when the antenna has been removed). SATCOM was also added, and in future Pavehawks I'm told that the HF antenna along the left lower tail boom (long towel rack) will be removed due to SATCOM taking over the long range secure Comm role. GPS was added in one of the initial Block 152 upgrades along with the AN/AAQ-16B FLIR, and the latest upgrade is supposed to give us external gun mounts outside the gunner's and FE's window along with external ammo boxes under the same windows. This will really free up the interior concerning storage space for gear and operators (something that has ALWAYS been a problem with the Pavehawk and was one of the big reasons AFSOC did away with the MH-60G). We will also be able to mount a .50 cal on these mounts along with the GAU-2B minigun, and M-240. We will then be able to mount a .50 on one side and a GAU-2B on the other...one for high rates of fire and the other for a longer range and hard target capability. By the way, the .50's mounted in the doorways really look cool, but they really were not a viable system mainly due to problems with exiting and entering the bird, hoist ops, rappel ops, etc... To my knowledge they have never been used operationally from the door mounts...at least my squadron never has and I've never seen them on any of my deployments.
So there you have it. All of the Pavehawks are in various stages of Block 152 upgrades and it's not uncommon to see differently configured birds in the same squadron (my squadron is like that now), at least until they have all been through Depo. With the advent of AFSOC taking over as the lead agency in the USAF for CSAR, the birds are now coming back from Depo painted AFSOC gray. Hell, my squadron is a PACAF unit and we're seeing our birds coming back from Depo gray.
Kinda long, but hope that helps.
Salbando