The three photos below were provided by Gary Herbert, a 174th Dolphin crewchief in 1967-68. The scan resolution is low so that details in the photos are poor (will try to get higher resolution scans). Few specifics are known on this emergency landing just now. Until I get more information I am listing this in 1967. It may have been in 1968. Will adjust the caption when I get more information. If any of you viewing this have details, please forward them to me (Webmaster) and I'll update the caption.
In the first photo, note that the vertical fin with the entire tailrotor assembly has either been severed by main rotor blade flexing or broken off during the landing, possibly by the stinger making contact with the ground in a steep flare and causing a structural failure in the aft end of the tail boom. You can see the fin is laying on the ground behind the helicopter.
Gary said in a note to me, "The best I can remember of this incident, and I might be real wrong, is that it happened right behind the Duc Pho mountain. I can't identify any of the people in the pictures..." The middle photo definitely has 67/68-vintage Dolphin nose art of the 1st flight platoon (yellow scarf on the Dolphin--2nd platoon was red), and the hill in the background is in fact Duc Pho mountain. It looks like the photo is taken south or southwest of Duc Pho, looking generally north.
Looking at the third photo, the skids are not noticeably bent, so actually the landing itself was not exceptionally hard. If this aircraft did in fact experience an engine failure or tail rotor failure in flight, I'd call this a successful emergency landing because the aircraft remained upright, the skids were not bent, there were probably no injuries to crew or passengers, and the aircraft is repairable and was probably fixed and returned to the inventory in short order. (Photos taken by Gary Herbert, Duc Pho, 1967 or 68)