The Patch you are questioning is definitely an LVTH-6 patch, although as a former H-6 Battery Commander stationed at Treasure Island (in San Francisco Bay), I never saw the patch. The H-6, a 1st Wave assault vehicle, never really had an impact since it was really never deployed properly. At one point, in the Vietnam era, our unit and our sister unit at Camp Lejuene, were placed on alert, to replace the Navy's "Swift Boats" in the Delta area. Since we were armored and mechanized, we would have been able to leave the rivers, go ashore with Infantary support and chase the " bad guys." Good thinking … but we were never activated and deployed.