Australian Geodetic Datum 1966 - ESRI:115878

WKT

VERTCS["Australian_1966", 
	DATUM["D_Australian_1966", 
		SPHEROID["Australian", 6378160.0, 298.25]], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["Australian_1966", 
	DATUM["D_Australian_1966", 
		ELLIPSOID["Australian", 6378160.0, 298.25]], 
	CS[vertical, 1], 
	AXIS["Ellipsoidal height (h)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["Esri", "115878"]]

Data from @esri/proj-codes

{
  "wkid": 115878,
  "latestWkid": 115878,
  "macro": "PE_VCS_AGD_1966",
  "name": "Australian_1966",
  "wkt": "VERTCS[\"Australian_1966\",DATUM[\"D_Australian_1966\",SPHEROID[\"Australian\",6378160.0,298.25]],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"Australian_1966\",DATUM[\"D_Australian_1966\",ELLIPSOID[\"Australian\",6378160.0,298.25]],CS[vertical,1],AXIS[\"Ellipsoidal height (h)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"Esri\",\"115878\"]]",
  "description": "Australian Geodetic Datum 1966",
  "authority": "Esri",
  "version": "13.0.0",
  "deprecated": "no",
  "areaname": "Australasia - Australia and PNG - AGD66",
  "extent": {
    "slat": -47.2,
    "nlat": -1.3,
    "llon": 109.23,
    "rlon": 163.2
  }
}