NGVD29 height (Meters) - EPSG:7968

WKT

VERTCS["NGVD_1929_height_(m)", 
	VDATUM["National_Geodetic_Vertical_Datum_1929"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["NGVD_1929_height_(m)", 
	VDATUM["National_Geodetic_Vertical_Datum_1929"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "7968"]]

Data from @esri/proj-codes

{
  "wkid": 7968,
  "latestWkid": 7968,
  "macro": "PE_VCS_NGVD29_HT_M",
  "name": "NGVD_1929_height_(m)",
  "wkt": "VERTCS[\"NGVD_1929_height_(m)\",VDATUM[\"National_Geodetic_Vertical_Datum_1929\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"NGVD_1929_height_(m)\",VDATUM[\"National_Geodetic_Vertical_Datum_1929\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"7968\"]]",
  "description": "NGVD29 height (Meters)",
  "authority": "EPSG",
  "version": "9.2(10.8.0)",
  "deprecated": "no",
  "areaname": "USA - CONUS - onshore",
  "extent": {
    "slat": 24.41,
    "nlat": 49.38,
    "llon": -124.79,
    "rlon": -66.91
  }
}